@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700;800;900&display=swap');

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
canvas { display: block; }

:root {
  --primary: #6366f1;
  --primary-dark: #4f46e5;
  --primary-darker: #3730a3;
  --primary-light: #eef2ff;
  --accent: #06b6d4;
  --success: #10b981;
  --danger: #ef4444;
  --warning: #f59e0b;
  --bg: #f1f5f9;
  --card: #ffffff;
  --text: #0f172a;
  --muted: #64748b;
  --border: #e2e8f0;
  --sidebar-w: 248px;
  --radius: 14px;
  --shadow: 0 1px 3px rgba(0,0,0,.06), 0 4px 16px rgba(0,0,0,.06);
  --shadow-md: 0 4px 24px rgba(0,0,0,.10);
  --shadow-lg: 0 8px 40px rgba(0,0,0,.14);
}

/* ===================== DARK MODE ===================== */
body.dark-mode {
  --bg: #0f172a;
  --card: #1e293b;
  --text: #e2e8f0;
  --muted: #94a3b8;
  --border: #334155;
  --primary-light: #1e1b4b;
  --shadow: 0 1px 3px rgba(0,0,0,.3), 0 4px 12px rgba(0,0,0,.2);
  --shadow-md: 0 4px 24px rgba(0,0,0,.4);
  --shadow-lg: 0 8px 40px rgba(0,0,0,.5);
}
body.dark-mode .data-table tbody tr:hover { background: #263548; }
body.dark-mode input:not([type="checkbox"]),
body.dark-mode select,
body.dark-mode textarea { background: #0f172a !important; color: var(--text) !important; border-color: var(--border) !important; }
body.dark-mode .mini-table th,
body.dark-mode .data-table th { background: #0f172a; }
body.dark-mode #darkModeBtn { background: #334155 !important; border-color: #475569 !important; }

body { font-family: 'Inter', 'Segoe UI', system-ui, sans-serif; color: var(--text); background: var(--bg); -webkit-font-smoothing: antialiased; }
a { text-decoration: none; color: inherit; }
input, select, button, textarea { font-family: inherit; font-size: 0.95rem; }

/* ===================== AUTH ===================== */
body.auth-page {
  background: #f0f4ff;
  min-height: 100vh;
  display: flex;
  align-items: stretch;
}

.auth-wrap {
  display: flex;
  width: 100%;
  min-height: 100vh;
}

.auth-left {
  flex: 0 0 55%;
  background: linear-gradient(145deg, #0f0c29 0%, #1a1a4e 45%, #302b63 100%);
  color: #fff;
  display: flex;
  flex-direction: column;
  justify-content: center;
  padding: 3.5rem;
  position: relative;
  overflow: hidden;
}

.auth-left::before {
  content: '';
  position: absolute;
  top: -120px; right: -120px;
  width: 420px; height: 420px;
  background: radial-gradient(circle, rgba(99,102,241,.25) 0%, transparent 70%);
  border-radius: 50%;
}

.auth-left::after {
  content: '';
  position: absolute;
  bottom: -80px; left: -80px;
  width: 320px; height: 320px;
  background: radial-gradient(circle, rgba(6,182,212,.18) 0%, transparent 70%);
  border-radius: 50%;
}

.auth-left > * { position: relative; z-index: 1; }

.brand { font-size: 1.25rem; font-weight: 800; color: var(--primary); white-space: nowrap; }
.auth-left .brand.white { color: #fff; font-size: 1.5rem; letter-spacing: -.3px; }

.auth-left h2 {
  font-size: 2.4rem;
  font-weight: 900;
  margin-top: 2rem;
  line-height: 1.2;
  letter-spacing: -.5px;
}

.auth-left p {
  opacity: .8;
  font-size: 1.05rem;
  margin-top: .75rem;
  max-width: 360px;
  line-height: 1.6;
}

.auth-features {
  margin-top: 2.5rem;
  display: flex;
  flex-direction: column;
  gap: .75rem;
}

.auth-feature-item {
  display: flex;
  align-items: center;
  gap: .85rem;
  background: rgba(255,255,255,.07);
  backdrop-filter: blur(8px);
  padding: .85rem 1.1rem;
  border-radius: 14px;
  border: 1px solid rgba(255,255,255,.08);
  transition: background .2s;
}

.auth-feature-item:hover { background: rgba(255,255,255,.12); }

.auth-feature-icon {
  font-size: 1.5rem;
  flex-shrink: 0;
  width: 40px;
  height: 40px;
  background: rgba(255,255,255,.1);
  border-radius: 10px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.auth-feature-text .title { font-weight: 700; font-size: .9rem; }
.auth-feature-text .sub { font-size: .76rem; opacity: .65; margin-top: .1rem; }

.auth-right {
  flex: 0 0 45%;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 2.5rem 2rem;
  background: #f0f4ff;
}

.auth-box {
  background: rgba(255,255,255,.98);
  border-radius: 28px;
  padding: 2.5rem 2.25rem;
  width: 100%;
  max-width: 420px;
  box-shadow: 0 32px 80px rgba(99,102,241,.18), 0 2px 8px rgba(0,0,0,.06), inset 0 1px 0 rgba(255,255,255,.9);
  border: 1px solid rgba(99,102,241,.12);
  display: flex;
  flex-direction: column;
  gap: .85rem;
  backdrop-filter: blur(20px);
}

.auth-box-header { text-align: center; margin-bottom: .25rem; }
.auth-box-header .emoji { font-size: 2.2rem; margin-bottom: .5rem; }
.auth-box-header h2 { font-size: 1.65rem; font-weight: 900; color: #0f172a; letter-spacing: -.4px; }
.auth-box-header p { font-size: .85rem; color: var(--muted); margin-top: .3rem; }

.auth-box label { font-size: .82rem; font-weight: 600; color: var(--muted); letter-spacing: .2px; }

.input-icon {
  display: flex;
  align-items: center;
  border: 1.5px solid var(--border);
  border-radius: 10px;
  overflow: hidden;
  background: #fafbff;
  transition: border-color .2s, box-shadow .2s;
}

.input-icon:focus-within {
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(99,102,241,.12);
  background: #fff;
}

.input-icon span { padding: 0 .85rem; color: var(--muted); font-size: 1rem; }
.input-icon input {
  flex: 1;
  border: none;
  outline: none;
  padding: .75rem .5rem .75rem 0;
  background: transparent;
  font-size: .95rem;
  color: var(--text);
}

.auth-row { display: flex; justify-content: space-between; align-items: center; font-size: .84rem; }
.checkbox-label { display: flex; align-items: center; gap: .4rem; color: var(--muted); cursor: pointer; }
.link-muted { color: var(--muted); transition: color .2s; }
.link-muted:hover { color: var(--primary); }
.auth-hint { text-align: center; font-size: .84rem; color: var(--muted); }

/* ===================== DASHBOARD ===================== */
body.dashboard-page { display: flex; min-height: 100vh; background: var(--bg); }

/* Sidebar */
.sidebar {
  width: var(--sidebar-w);
  background: linear-gradient(180deg, #1e1b4b 0%, #312e81 100%);
  transition: width .25s ease, transform .3s ease;
  color: #fff;
  display: flex;
  flex-direction: column;
  position: fixed;
  top: 0; left: 0;
  height: 100vh;
  z-index: 200;
  transition: transform .3s;
  box-shadow: 4px 0 24px rgba(0,0,0,.15);
  overflow: hidden;
}

.sidebar-brand {
  padding: 0 1.25rem;
  height: 62px;
  font-size: 1rem;
  font-weight: 800;
  border-bottom: 1px solid rgba(255,255,255,.08);
  display: flex;
  align-items: center;
  gap: .65rem;
  flex-shrink: 0;
  letter-spacing: -.2px;
}

.sidebar-brand-icon {
  width: 34px; height: 34px;
  background: rgba(255,255,255,.12);
  border-radius: 10px;
  display: flex; align-items: center; justify-content: center;
  font-size: 1rem;
  flex-shrink: 0;
}

.sidebar-brand-text { white-space: nowrap; overflow: hidden; text-overflow: ellipsis; max-width: 160px; }

.sidebar-nav {
  flex: 1;
  padding: .75rem .75rem;
  display: flex;
  flex-direction: column;
  gap: .15rem;
  overflow-y: auto;
}

.slink {
  display: flex;
  align-items: center;
  gap: .7rem;
  padding: .65rem .9rem;
  color: rgba(255,255,255,.65);
  font-size: .875rem;
  font-weight: 500;
  transition: background .18s, color .18s;
  cursor: pointer;
  border-radius: 10px;
  white-space: nowrap;
}

.slink-icon { font-size: 1rem; flex-shrink: 0; width: 20px; text-align: center; }
.slink-label { flex: 1; }

.slink:hover { background: rgba(255,255,255,.1); color: #fff; }
.slink.active {
  background: rgba(255,255,255,.15);
  color: #fff;
  font-weight: 600;
  box-shadow: inset 3px 0 0 rgba(165,180,252,.8);
}

.slink-logout { margin: .4rem .75rem; color: rgba(255,255,255,.5); border-radius: 10px; }
.slink-logout:hover { color: #fca5a5; background: rgba(239,68,68,.15); }

/* Main */
.dash-main { margin-left: var(--sidebar-w); flex: 1; display: flex; flex-direction: column; min-height: 100vh; transition: margin-left .3s; }

/* Sidebar collapsed (desktop) */
body.sidebar-collapsed .sidebar { transform: translateX(-100%); }
body.sidebar-collapsed .dash-main { margin-left: 0; }

/* Sidebar mini — chỉ hiện icon */
@media (min-width: 769px) {
  body.sidebar-mini .sidebar { width: 68px; overflow: hidden; }
  body.sidebar-mini .dash-main { margin-left: 68px; }
  body.sidebar-mini .sidebar-brand-text { display: none; }
  body.sidebar-mini .slink-label { display: none; }
  body.sidebar-mini .sidebar-brand {
    justify-content: center;
    padding: 0;
    border-bottom: 1px solid rgba(255,255,255,.08);
  }
  body.sidebar-mini .sidebar-brand-icon {
    width: 38px; height: 38px;
    margin: 0;
  }
  body.sidebar-mini .sidebar-mini-toggle {
    display: none;
  }
  body.sidebar-mini .sidebar-nav {
    padding: .6rem .5rem;
    gap: .25rem;
    align-items: center;
    overflow: hidden;
  }
  body.sidebar-mini .sidebar-mini-reopen {
    display: flex !important;
  }
  body.sidebar-mini .sidebar-mini-reopen button {
    display: flex !important;
  }
  body.sidebar-mini .slink {
    justify-content: center;
    padding: .7rem 0;
    width: 48px;
    border-radius: 12px;
    position: relative;
  }
  body.sidebar-mini .slink-icon {
    width: auto;
    font-size: 1.25rem;
  }
  body.sidebar-mini .slink.active {
    background: rgba(255,255,255,.18);
    box-shadow: none;
  }
  body.sidebar-mini .slink.active::before {
    content: '';
    position: absolute;
    left: 0; top: 50%;
    transform: translateY(-50%);
    width: 3px; height: 60%;
    background: rgba(165,180,252,.9);
    border-radius: 0 3px 3px 0;
  }
  /* Tooltip khi hover */
  body.sidebar-mini .slink::after {
    content: attr(data-label);
    position: fixed;
    left: 76px;
    background: #1e1b4b;
    color: #fff;
    font-size: .78rem;
    font-weight: 600;
    padding: .35rem .75rem;
    border-radius: 8px;
    white-space: nowrap;
    pointer-events: none;
    opacity: 0;
    transform: translateX(-6px);
    transition: opacity .15s, transform .15s;
    box-shadow: 0 4px 16px rgba(0,0,0,.25);
    z-index: 9999;
  }
  body.sidebar-mini .slink:hover::after {
    opacity: 1;
    transform: translateX(0);
  }
  body.sidebar-mini .nav-badge { display: none !important; }
  body.sidebar-mini #sidebarOnlineBadge { display: none !important; }
  body.sidebar-mini .slink-logout { width: 48px; margin: .4rem auto; }
  /* Version label ẩn */
  body.sidebar-mini .sidebar-version { display: none; }
}

/* Nút mở lại sidebar khi đang mini */
.sidebar-mini-reopen {
  display: none;
  justify-content: center;
  padding: .6rem 0 .8rem;
  flex-shrink: 0;
}
.sidebar-mini-reopen button {
  background: rgba(255,255,255,.1);
  border: 1px solid rgba(255,255,255,.15);
  color: rgba(255,255,255,.7);
  width: 36px; height: 36px;
  border-radius: 10px;
  cursor: pointer;
  font-size: .9rem;
  display: flex; align-items: center; justify-content: center;
  transition: all .2s;
}
.sidebar-mini-reopen button:hover {
  background: rgba(255,255,255,.2);
  color: #fff;
}

/* Topbar */
.topbar {
  background: var(--card);
  border-bottom: 1px solid var(--border);
  height: 62px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 1.75rem;
  position: sticky;
  top: 0;
  z-index: 150;
  box-shadow: 0 1px 0 var(--border);
}

/* Sidebar bắt đầu từ dưới topbar trên desktop */
@media (min-width: 769px) {
  .sidebar {
    top: 0;
    z-index: 100;
  }
}

.menu-toggle { display: block; background: none; border: none; font-size: 1.4rem; cursor: pointer; color: var(--text); }
.topbar-right { display: flex; align-items: center; gap: 1rem; }
.avatar-info { display: flex; align-items: center; gap: .75rem; }

.avatar {
  width: 38px; height: 38px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--primary), var(--accent));
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: .78rem;
  font-weight: 700;
  box-shadow: 0 2px 8px rgba(99,102,241,.3);
}

.av-name { font-weight: 700; font-size: .9rem; }
.av-role { font-size: .75rem; color: var(--muted); }

/* Pages */
.page { display: none; padding: 2rem 1.75rem; }
.page.active { display: block; }
.page-title { font-size: 1.5rem; font-weight: 800; margin-bottom: 1.5rem; letter-spacing: -.3px; }
.page-header { display: flex; align-items: center; justify-content: space-between; margin-bottom: 1.25rem; }
.page-header .page-title { margin-bottom: 0; }

/* Stats */
.stat-grid { display: grid; grid-template-columns: repeat(4,1fr); gap: 1.1rem; margin-bottom: 1.5rem; }

.stat-card {
  background: var(--card);
  border-radius: var(--radius);
  padding: 1.35rem 1.5rem;
  display: flex;
  align-items: center;
  gap: 1rem;
  box-shadow: var(--shadow);
  border: 1px solid var(--border);
  border-left: 4px solid transparent;
  transition: transform .2s, box-shadow .2s;
}

.stat-card:hover { transform: translateY(-2px); box-shadow: var(--shadow-md); }
.stat-card.blue   { border-left-color: #3b82f6; }
.stat-card.green  { border-left-color: var(--success); }
.stat-card.purple { border-left-color: var(--primary); }
.stat-card.orange { border-left-color: var(--warning); }
.stat-card.red    { border-left-color: var(--danger); }
.stat-icon { font-size: 2rem; }
.stat-num  { font-size: 1.9rem; font-weight: 800; line-height: 1; letter-spacing: -.5px; }
.stat-label { font-size: .8rem; color: var(--muted); margin-top: .25rem; font-weight: 500; }

/* Overview panels */
.overview-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 1.5rem; }

.overview-panel {
  background: var(--card);
  border-radius: var(--radius);
  padding: 1.35rem;
  box-shadow: var(--shadow);
  border: 1px solid var(--border);
}

.panel-header { display: flex; justify-content: space-between; align-items: center; margin-bottom: 1rem; font-weight: 700; font-size: .95rem; }
.link-blue { color: var(--primary); font-size: .82rem; font-weight: 600; }
.link-blue:hover { text-decoration: underline; }

/* List rows */
.list-row { display: flex; align-items: center; gap: .75rem; padding: .7rem 0; border-bottom: 1px solid var(--border); }
.list-row:last-child { border-bottom: none; }
.list-row.clickable { cursor: pointer; border-radius: 10px; padding: .7rem .6rem; transition: background .15s; }
.list-row.clickable:hover { background: var(--primary-light); }
.list-icon { font-size: 1.4rem; flex-shrink: 0; }
.list-title { font-weight: 600; font-size: .9rem; }
.list-meta  { font-size: .77rem; color: var(--muted); margin-top: .15rem; }
.muted-sm   { color: var(--muted); font-size: .88rem; padding: .5rem 0; }

/* Filter bar */
.filter-bar { display: flex; gap: .75rem; margin-bottom: 1.25rem; flex-wrap: wrap; }

.filter-bar input, .filter-bar select {
  padding: .55rem 1rem;
  border: 1.5px solid var(--border);
  border-radius: 10px;
  outline: none;
  background: var(--card);
  font-size: .88rem;
  transition: border-color .2s;
}

.filter-bar input:focus, .filter-bar select:focus { border-color: var(--primary); }

/* Content list */
.content-list { display: flex; flex-direction: column; gap: .6rem; }

.content-row {
  background: var(--card);
  border: 1.5px solid var(--border);
  border-radius: var(--radius);
  padding: 1rem 1.25rem;
  display: flex;
  align-items: center;
  gap: .75rem;
  box-shadow: var(--shadow);
  transition: border-color .2s, box-shadow .2s;
}

.content-row.clickable { cursor: pointer; }
.content-row.clickable:hover { border-color: var(--primary); box-shadow: 0 4px 16px rgba(99,102,241,.12); }
.row-actions { margin-left: auto; display: flex; gap: .5rem; }

/* Video grid */
.video-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(260px,1fr)); gap: 1.25rem; }

.video-card {
  background: var(--card);
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: var(--shadow);
  border: 1.5px solid var(--border);
  transition: transform .2s, box-shadow .2s;
}

.video-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-md); }
.video-thumb { position: relative; height: 160px; background: #1e1b4b; cursor: pointer; overflow: hidden; }
.video-thumb video { width: 100%; height: 100%; object-fit: cover; pointer-events: none; }

.play-btn {
  position: absolute; inset: 0;
  display: flex; align-items: center; justify-content: center;
  font-size: 2.5rem; color: #fff; opacity: .85;
  transition: opacity .2s;
  background: rgba(0,0,0,.2);
}

.video-thumb:hover .play-btn { opacity: 1; }

.subject-tag {
  position: absolute; top: 8px; left: 8px;
  background: var(--primary); color: #fff;
  font-size: .7rem; font-weight: 700;
  padding: .2rem .65rem; border-radius: 20px;
}

.video-info { padding: .9rem 1rem; }
.video-title { font-weight: 700; font-size: .9rem; margin-bottom: .3rem; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.video-meta  { font-size: .78rem; color: var(--muted); margin-bottom: .6rem; }

/* Two-col layout */
.two-col { display: grid; grid-template-columns: minmax(280px, 380px) 1fr; gap: 1.5rem; align-items: start; }
@media (max-width: 820px) {
  .two-col { grid-template-columns: 1fr; }
}

/* Form panel */
.form-panel {
  background: var(--card);
  border-radius: var(--radius);
  padding: 1.5rem;
  box-shadow: var(--shadow);
  border: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  gap: .75rem;
}

.form-panel h3 { font-size: 1rem; font-weight: 700; margin-bottom: .25rem; }
.form-panel label { font-size: .82rem; font-weight: 600; color: var(--muted); }

.form-panel input, .form-panel select, .form-panel textarea {
  padding: .65rem .9rem;
  border: 1.5px solid var(--border);
  border-radius: 10px;
  outline: none;
  transition: border-color .2s;
}

.form-panel input:focus, .form-panel select:focus, .form-panel textarea:focus { border-color: var(--primary); }
.form-actions { display: flex; gap: .75rem; justify-content: flex-end; margin-top: .25rem; }

/* Mini table */
.mini-table { width: 100%; border-collapse: collapse; font-size: .85rem; }
.mini-table th, .mini-table td { padding: .6rem .75rem; text-align: left; border-bottom: 1px solid var(--border); }
.mini-table th { color: var(--muted); font-size: .73rem; text-transform: uppercase; background: var(--bg); font-weight: 700; letter-spacing: .3px; }

/* Pagination */
.table-pagination { display: flex; gap: .4rem; margin-top: .75rem; flex-wrap: wrap; }
.page-btn { padding: .3rem .7rem; border: 1.5px solid var(--border); border-radius: 8px; background: var(--card); cursor: pointer; font-size: .82rem; transition: all .15s; }
.page-btn:hover { border-color: var(--primary); color: var(--primary); }
.page-btn.active { background: var(--primary); color: #fff; border-color: var(--primary); }

/* Data table */
.data-table { width: 100%; border-collapse: collapse; background: var(--card); border-radius: var(--radius); overflow: hidden; box-shadow: var(--shadow); border: 1px solid var(--border); }
.data-table th, .data-table td { padding: .8rem 1rem; text-align: left; border-bottom: 1px solid var(--border); font-size: .87rem; }
.data-table th { background: var(--bg); font-size: .75rem; text-transform: uppercase; color: var(--muted); font-weight: 700; letter-spacing: .3px; }
.data-table tr:last-child td { border-bottom: none; }
.data-table tbody tr:hover { background: #fafbff; }

/* Profile */
.profile-card {
  background: var(--card);
  border-radius: var(--radius);
  padding: 1.75rem 2rem;
  display: flex;
  align-items: center;
  gap: 1.5rem;
  box-shadow: var(--shadow);
  border: 1px solid var(--border);
  max-width: 480px;
}

.profile-avatar {
  width: 68px; height: 68px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--primary), var(--accent));
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.4rem;
  font-weight: 700;
  flex-shrink: 0;
  box-shadow: 0 4px 16px rgba(99,102,241,.3);
}

.profile-name { font-size: 1.2rem; font-weight: 800; }
.profile-role { color: var(--muted); font-size: .88rem; margin-top: .2rem; }
.profile-class { color: var(--primary); font-size: .88rem; margin-top: .2rem; font-weight: 600; }

/* ===================== BUTTONS ===================== */
.btn-primary {
  background: linear-gradient(135deg, var(--primary), var(--primary-dark));
  color: #fff;
  border: none;
  padding: .65rem 1.4rem;
  border-radius: 10px;
  font-weight: 700;
  cursor: pointer;
  transition: all .2s;
  display: inline-flex;
  align-items: center;
  gap: .4rem;
  box-shadow: 0 2px 8px rgba(99,102,241,.3);
  font-size: .9rem;
}

.btn-primary:hover {
  background: linear-gradient(135deg, var(--primary-dark), var(--primary-darker));
  box-shadow: 0 4px 16px rgba(99,102,241,.4);
  transform: translateY(-1px);
}

.btn-outline {
  background: transparent;
  color: var(--text);
  border: 1.5px solid var(--border);
  padding: .65rem 1.4rem;
  border-radius: 10px;
  font-weight: 600;
  cursor: pointer;
  transition: all .2s;
  display: inline-flex;
  align-items: center;
  gap: .4rem;
  font-size: .9rem;
}

.btn-outline:hover { background: var(--bg); border-color: #cbd5e1; }
.btn-lg { padding: .85rem 2rem; font-size: 1rem; border-radius: 12px; }
.btn-block { width: 100%; justify-content: center; }

.btn-sm {
  padding: .3rem .75rem;
  border-radius: 8px;
  font-size: .8rem;
  cursor: pointer;
  border: 1.5px solid var(--border);
  background: var(--card);
  color: var(--text);
  transition: all .2s;
  text-decoration: none;
  display: inline-flex;
  align-items: center;
  gap: .3rem;
  font-weight: 600;
}

.btn-sm:hover { background: var(--bg); }
.btn-danger { border-color: #fca5a5; color: var(--danger); }
.btn-danger:hover { background: #fee2e2; border-color: var(--danger); }
.btn-success { border-color: #6ee7b7; color: var(--success); }
.btn-success:hover { background: #d1fae5; border-color: var(--success); }

/* ===================== STATUS ===================== */
.status-badge { padding: .25rem .7rem; border-radius: 20px; font-size: .74rem; font-weight: 700; letter-spacing: .2px; }
.status-badge.active   { background: #d1fae5; color: #065f46; }
.status-badge.inactive { background: #fee2e2; color: #991b1b; }

/* ===================== MODAL ===================== */
.modal-overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(15,23,42,.55);
  backdrop-filter: blur(4px);
  z-index: 300;
  align-items: center;
  justify-content: center;
  padding: 1rem;
}

.modal-overlay.open { display: flex; }

.modal {
  background: var(--card);
  border-radius: 20px;
  padding: 2rem;
  width: 100%;
  max-width: 500px;
  display: flex;
  flex-direction: column;
  gap: .9rem;
  box-shadow: 0 24px 80px rgba(0,0,0,.2);
  max-height: 90vh;
  overflow-y: auto;
  border: 1px solid var(--border);
}

.modal h2 { font-size: 1.2rem; font-weight: 800; color: var(--primary); }
.modal label { font-size: .82rem; font-weight: 600; color: var(--muted); }

.modal input, .modal select, .modal textarea {
  padding: .65rem .9rem;
  border: 1.5px solid var(--border);
  border-radius: 10px;
  outline: none;
  transition: border-color .2s;
}

.modal input:focus, .modal select:focus, .modal textarea:focus { border-color: var(--primary); }
.modal-actions { display: flex; gap: .75rem; justify-content: flex-end; }

.modal-close {
  position: absolute;
  top: 1rem; right: 1rem;
  background: var(--bg);
  border: none;
  border-radius: 50%;
  width: 32px; height: 32px;
  cursor: pointer;
  font-size: 1rem;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background .2s;
}

.modal-close:hover { background: #cbd5e1; }

/* Upload drop zone */
.upload-drop {
  border: 2px dashed var(--border);
  border-radius: 12px;
  padding: 1.75rem;
  text-align: center;
  color: var(--muted);
  transition: border-color .2s, background .2s;
}

.upload-drop:hover { border-color: var(--primary); background: var(--primary-light); }
.upload-icon { font-size: 2.5rem; margin-bottom: .5rem; }
.upload-hint { font-size: .78rem; margin-top: .25rem; }
.file-info { font-size: .82rem; color: var(--primary); margin-top: .5rem; font-weight: 600; }

/* Preview video */
.preview-wrap video { width: 100%; border-radius: 10px; max-height: 200px; background: #000; }

/* Viewer modal */
.viewer-modal {
  width: 88vw !important;
  max-width: 88vw !important;
  min-width: 0 !important;
  height: 95vh !important;
  max-height: 95vh !important;
  position: relative;
  padding: .75rem !important;
  overflow: hidden;
  display: flex !important;
  flex-direction: column !important;
}
.viewer-modal h2 { font-size: .95rem; margin-bottom: 0; flex-shrink: 0; }
.viewer-modal .modal-actions { margin-top: .3rem; padding: 0; min-height: 0; flex-shrink: 0; }
#viewerBody { flex: 1; min-height: 0; display: flex; flex-direction: column; background: #0f172a; border-radius: 10px; overflow: hidden; }
#viewerBody iframe, #viewerBody video, #viewerBody img { flex: 1; min-height: 0; width: 100%; height: 100% !important; border: none; border-radius: 10px; background: #0f172a; }
#viewerBody video { background: #000; }
.viewer-video { width: 100%; border-radius: 10px; background: #000; max-height: 90vh; }
.viewer-iframe { width: 100%; height: 100% !important; border: none; border-radius: 10px; }
.viewer-img { width: 100%; max-height: 90vh; object-fit: contain; border-radius: 10px; }
.muted-center { text-align: center; padding: 3rem 1rem; color: var(--muted); }

/* ===================== MISC ===================== */
.error-msg   { color: var(--danger); font-size: .83rem; min-height: 1rem; font-weight: 500; }
.success-msg { color: var(--success); font-size: .83rem; min-height: 1rem; font-weight: 500; }
.empty-state { text-align: center; padding: 3rem 1rem; color: var(--muted); font-size: .95rem; }
.muted { color: var(--muted); font-weight: 400; font-size: .82rem; }

/* Tab row */
.tab-row { display: flex; border: 1.5px solid var(--border); border-radius: 12px; overflow: hidden; background: var(--bg); padding: 3px; gap: 3px; }

.tab-btn {
  flex: 1;
  padding: .55rem;
  border: none;
  background: none;
  cursor: pointer;
  font-size: .88rem;
  font-weight: 600;
  color: var(--muted);
  transition: all .2s;
  border-radius: 9px;
}

.tab-btn.active { background: #fff; color: var(--primary); box-shadow: 0 1px 4px rgba(0,0,0,.1); }

/* ===================== RESPONSIVE ===================== */
@media (max-width: 1024px) {
  .stat-grid { grid-template-columns: repeat(2,1fr); }
  .two-col { grid-template-columns: 1fr; }
}

@media (max-width: 768px) {
  .sidebar { transform: translateX(-100%); }
  .sidebar.open { transform: translateX(0); }
  .dash-main { margin-left: 0; }
  .menu-toggle { display: block; }
  .overview-grid { grid-template-columns: 1fr; }
  .auth-left { display: none; }
  .auth-right { flex: 1; }
  .auth-box { padding: 2rem 1.5rem; }
}

@media (max-width: 480px) {
  .stat-grid { grid-template-columns: 1fr 1fr; }
  .page { padding: 1.25rem 1rem; }
}

/* ===================== STUDENT PROFILE POLISH ===================== */
/* Tổng thể profile: spacing + cảm giác "app" */
#pageProfile > div {
  transition: transform .18s ease, box-shadow .18s ease, border-color .18s ease;
}

/* Profile hero: glass + glow */
.profile-hero::after{
  content:'';
  position:absolute;
  inset:0;
  background:
    radial-gradient(ellipse at 18% 18%, rgba(255,255,255,.12) 0%, transparent 45%),
    radial-gradient(ellipse at 85% 65%, rgba(6,182,212,.10) 0%, transparent 50%),
    radial-gradient(ellipse at 65% 25%, rgba(99,102,241,.16) 0%, transparent 50%);
  opacity:.9;
  pointer-events:none;
}

/* Overview cards: đồng bộ, nhìn "premium" */
.profile-overview{
  backdrop-filter: blur(14px);
}
.po-card{
  position: relative;
  overflow:hidden;
  box-shadow: 0 10px 26px rgba(0,0,0,.22);
  transition: transform .16s ease, box-shadow .16s ease, border-color .16s ease;
}
.po-card::before{
  content:'';
  position:absolute;
  inset:-1px;
  opacity:.85;
  pointer-events:none;
  background: radial-gradient(circle at 25% 20%, rgba(255,255,255,.18), transparent 55%);
}
.po-card .po-label,
.po-card .po-value{ position: relative; z-index: 1; }
.po-value{ letter-spacing: -.3px; }
@media (hover: hover) and (pointer: fine){
  .po-card:hover{ transform: translateY(-2px); box-shadow: 0 14px 34px rgba(0,0,0,.3); }
}

/* Màu nhấn nhẹ theo loại */
.po-blue{ border-color: rgba(129,140,248,.45) !important; }
.po-green{ border-color: rgba(74,222,128,.45) !important; }
.po-orange{ border-color: rgba(251,146,60,.55) !important; }
.po-cyan{ border-color: rgba(103,232,249,.45) !important; }

/* Lưới huy chương: đẹp và đều hơn */
#profileAchievementsGrid > div {
  box-shadow: 0 1px 3px rgba(0,0,0,.05);
  transition: transform .16s ease, box-shadow .16s ease, border-color .16s ease;
}
@media (hover: hover) and (pointer: fine) {
  #profileAchievementsGrid > div:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
    border-color: rgba(99,102,241,.35);
  }
}

/* Achievement cards (huy chương) */
.ach-card{
  border-radius: 14px;
  padding: .8rem .85rem;
  border: 1.5px solid var(--border);
  background: linear-gradient(135deg, #ffffff, #f8fafc);
  position: relative;
  overflow: hidden;
}
.ach-card::before{
  content:'';
  position:absolute;
  inset:-1px;
  background: radial-gradient(circle at 20% 15%, rgba(99,102,241,.14), transparent 55%),
              radial-gradient(circle at 85% 70%, rgba(6,182,212,.10), transparent 55%);
  opacity:.9;
  pointer-events:none;
}
.ach-card > *{ position: relative; z-index: 1; }
.ach-row{ display:flex; align-items:flex-start; justify-content:space-between; gap:.6rem; }
.ach-title{ font-size:.9rem; font-weight:900; color: var(--text); line-height:1.3; }
.ach-meta{ font-size:.74rem; color: var(--muted); margin-top:.25rem; line-height:1.55; }
.ach-pill{
  font-size:.68rem;
  font-weight:800;
  padding:.14rem .5rem;
  border-radius:999px;
  flex-shrink:0;
  border:1px solid transparent;
}
.ach-pill.ok{ background:#16a34a; color:#fff; border-color: rgba(22,163,74,.35); }
.ach-pill.no{ background:#e2e8f0; color:#475569; border-color: rgba(148,163,184,.45); }
.ach-bar{
  height:8px;
  background: rgba(148,163,184,.25);
  border-radius:999px;
  overflow:hidden;
  margin-top:.55rem;
}
.ach-bar-fill{
  height:100%;
  background: linear-gradient(90deg, #6366f1, #06b6d4, #10b981);
  border-radius:999px;
  opacity:.95;
}
.ach-unlocked{
  border-color: rgba(34,197,94,.35);
  background: linear-gradient(135deg, #ecfdf5, #f0fdf4);
}
.ach-locked{
  background: linear-gradient(135deg, #ffffff, #f8fafc);
}

@media (max-width: 768px){
  .ach-card{ padding:.75rem .8rem; border-radius: 14px; }
  .ach-title{ font-size:.88rem; }
  .ach-meta{ font-size:.73rem; }
}

/* Bảng thi đua: card item press on mobile */
#profileLeaderboardList > div {
  -webkit-tap-highlight-color: transparent;
}

/* --- Mobile: gom gọn profile --- */
@media (max-width: 768px) {
  /* Tránh tràn ngang do inline style */
  #pageProfile { overflow-x: hidden; }

  /* Header profile */
  #pageProfile > div:first-child {
    padding: 1.25rem 1.1rem 1.55rem !important;
    border-radius: 16px !important;
    box-shadow: 0 14px 34px rgba(15,23,42,.55) !important;
  }
  #profileAvatar {
    width: 62px !important;
    height: 62px !important;
    border-radius: 18px !important;
    font-size: 1.55rem !important;
  }
  #profileName { font-size: 1.15rem !important; }
  #profileClass { max-width: 100% !important; }

  /* Quick overview (4 ô) */
  #pageProfile > div:nth-child(2),
  .profile-overview {
    padding: .85rem .85rem .8rem !important;
    border-radius: 0 0 14px 14px !important;
    margin-bottom: 1rem !important;
  }
  #pageProfile > div:nth-child(2) > div,
  .profile-overview-grid {
    grid-template-columns: 1fr 1fr !important;
    gap: .5rem !important;
  }
  #pageProfile > div:nth-child(2) > div > div,
  .po-card {
    border-radius: 12px !important;
    padding: .6rem .65rem !important;
  }
  #profileQuickPoints,
  #profileQuickHours,
  #profileQuickStreak,
  #profileQuickBadges {
    font-size: 1.05rem !important;
  }

  /* Card "Thông tin khóa học" */
  #pageProfile > div:nth-child(3) {
    border-radius: 14px !important;
    padding: 1rem !important;
  }
  #pageProfile > div:nth-child(3) > div[style*="grid-template-columns"] {
    grid-template-columns: 1fr !important;
  }

  /* Card huy chương + streak */
  #pageProfile > div:nth-child(4),
  #pageProfile > div:nth-child(5) {
    border-radius: 14px !important;
  }
  #profilePointRules {
    padding: .65rem .7rem !important;
    border-radius: 12px !important;
  }
  #profileStreakValue { font-size: .9rem !important; }
  #profileStreakStatus { line-height: 1.55 !important; }
  #profileAchievementsGrid {
    grid-template-columns: 1fr !important;
    gap: .55rem !important;
  }
}

@media (max-width: 420px) {
  /* Quick overview 1 cột trên màn rất nhỏ */
  #pageProfile > div:nth-child(2) > div {
    grid-template-columns: 1fr !important;
  }
}

/* Class tag */
.class-tag { background: var(--primary-light); color: var(--primary); font-weight: 700; padding: .15rem .55rem; border-radius: 8px; font-size: .76rem; }

/* ===================== SECURITY OVERLAY ===================== */
#securityOverlay {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,.95);
  z-index: 9999;
  align-items: center;
  justify-content: center;
}

#securityOverlay.active { display: flex; }

.sec-box {
  text-align: center;
  color: #fff;
  padding: 2.5rem;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 1rem;
  max-width: 420px;
  background: rgba(255,255,255,.04);
  border-radius: 20px;
  border: 1px solid rgba(255,255,255,.1);
}

.sec-icon { font-size: 4rem; }
.sec-box h2 { font-size: 1.5rem; font-weight: 800; color: #ef4444; }
.sec-box p { color: rgba(255,255,255,.75); line-height: 1.7; font-size: .95rem; }

.sec-box button {
  margin-top: .5rem;
  background: var(--primary);
  color: #fff;
  border: none;
  padding: .75rem 2rem;
  border-radius: 10px;
  font-size: 1rem;
  font-weight: 700;
  cursor: pointer;
  transition: background .2s;
}

.sec-box button:hover { background: var(--primary-dark); }

/* Chặn chọn text */
body.dashboard-page { -webkit-user-select: none; user-select: none; }

/* Alert */
.alert-badge { background: #fee2e2; color: #991b1b; font-size: .74rem; font-weight: 700; padding: .15rem .55rem; border-radius: 8px; }

/* Nav badge */
.nav-badge {
  background: #ef4444;
  color: #fff;
  font-size: .67rem;
  font-weight: 700;
  padding: .1rem .45rem;
  border-radius: 20px;
  margin-left: .4rem;
  animation: badgePop .3s ease;
}

@keyframes badgePop {
  0%   { transform: scale(0); }
  70%  { transform: scale(1.3); }
  100% { transform: scale(1); }
}

@keyframes spin {
  to { transform: rotate(360deg); }
}
  100% { transform: scale(1); }
}

/* Landing */
body.landing { background: #fff; }
.land-nav { background: #fff; border-bottom: 1px solid var(--border); position: sticky; top: 0; z-index: 100; }
.land-nav-inner { max-width: 1100px; margin: 0 auto; padding: 0 1.5rem; height: 64px; display: flex; align-items: center; gap: 2rem; }
.land-nav-links { display: flex; gap: 1.5rem; flex: 1; }
.land-nav-links a { color: var(--muted); font-size: .95rem; transition: color .2s; }
.land-nav-links a:hover { color: var(--primary); }
.land-nav-btns { display: flex; gap: .75rem; }
.land-footer { text-align: center; padding: 2rem; color: var(--muted); font-size: .85rem; border-top: 1px solid var(--border); }


/* ===================== GROUP ACCORDION ===================== */

.group-card-grid {
  display: flex;
  flex-direction: column;
  gap: .5rem;
}

.group-card {
  background: var(--card);
  border-radius: 14px;
  overflow: hidden;
  border: 1.5px solid var(--border);
  transition: border-color .2s, box-shadow .2s;
}

.group-card:hover { border-color: var(--gc, var(--primary)); box-shadow: 0 2px 12px var(--gc-glow, rgba(99,102,241,.1)); }
.group-card::before { display: none; }

/* Header — toàn bộ hàng bấm được */
.group-card-header {
  display: flex;
  align-items: center;
  gap: .85rem;
  padding: .9rem 1.1rem;
  cursor: pointer;
  user-select: none;
  position: relative;
  transition: background .15s;
}

.group-card-header::after {
  content: '';
  position: absolute;
  left: 0; top: 20%; bottom: 20%;
  width: 3px;
  background: var(--gc, var(--primary));
  border-radius: 0 3px 3px 0;
  opacity: .7;
  transition: opacity .2s, top .2s, bottom .2s;
}

.group-card.open .group-card-header {
  background: var(--gc-light, var(--primary-light));
}

.group-card.open .group-card-header::after {
  top: 0; bottom: 0; opacity: 1;
}

.group-card-icon {
  width: 36px; height: 36px;
  background: var(--gc-light, var(--primary-light));
  border-radius: 10px;
  display: flex; align-items: center; justify-content: center;
  font-size: 1.05rem;
  flex-shrink: 0;
  transition: background .2s;
}

.group-card.open .group-card-icon {
  background: var(--gc, var(--primary));
  box-shadow: 0 2px 8px var(--gc-glow, rgba(99,102,241,.3));
}

.group-card-body { flex: 1; min-width: 0; padding: 0; }

.group-card-name {
  font-size: .92rem;
  font-weight: 700;
  color: var(--text);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.group-card-meta { display: flex; align-items: center; gap: .5rem; margin-top: .15rem; }

.group-card-count {
  font-size: .72rem;
  color: var(--muted);
  font-weight: 500;
}

.group-card-actions {
  display: flex; gap: .35rem;
  opacity: 0; transition: opacity .15s; flex-shrink: 0;
}
.group-card:hover .group-card-actions { opacity: 1; }

/* Chevron */
.group-card-chevron {
  width: 26px; height: 26px;
  border-radius: 7px;
  background: var(--bg);
  display: flex; align-items: center; justify-content: center;
  font-size: .7rem; color: var(--muted);
  flex-shrink: 0;
  transition: transform .25s, background .15s, color .15s;
}

.group-card.open .group-card-chevron {
  transform: rotate(180deg);
  background: var(--gc, var(--primary));
  color: #fff;
}

.group-card-toggle { display: none; }

/* Lesson list */
.group-lesson-list {
  overflow: hidden;
  max-height: 0;
  transition: max-height .32s cubic-bezier(.4,0,.2,1);
  background: #f8faff;
}

.group-lesson-list.open {
  max-height: 9999px;
  border-top: 1px solid var(--border);
}

.group-lesson-list-inner {
  padding: .5rem .75rem .65rem;
  display: flex;
  flex-direction: column;
  gap: .3rem;
}

.group-lesson-item {
  display: flex;
  align-items: center;
  gap: .7rem;
  padding: .6rem .8rem;
  border-radius: 10px;
  cursor: pointer;
  transition: background .13s, transform .13s, box-shadow .13s;
  border: 1px solid transparent;
  background: var(--card);
  box-shadow: 0 1px 2px rgba(0,0,0,.04);
}

.group-lesson-item:hover {
  background: var(--gc-light, var(--primary-light));
  border-color: var(--gc, var(--primary));
  transform: translateX(3px);
  box-shadow: 0 2px 8px var(--gc-glow, rgba(99,102,241,.1));
}

.group-lesson-num { display: none; }

.group-lesson-info { flex: 1; min-width: 0; }

.group-lesson-title {
  font-size: .875rem; font-weight: 700;
  white-space: nowrap; overflow: hidden; text-overflow: ellipsis;
  color: var(--text);
}

.group-lesson-stats {
  font-size: .72rem; color: var(--muted);
  margin-top: .12rem;
  display: flex; gap: .45rem; align-items: center;
}

.group-lesson-item-actions {
  display: flex; align-items: center; gap: .3rem;
  flex-shrink: 0; opacity: 0; transition: opacity .13s;
}
.group-lesson-item:hover .group-lesson-item-actions { opacity: 1; }

.group-lesson-open {
  width: 28px; height: 28px;
  border-radius: 8px;
  background: var(--gc-light, var(--primary-light));
  border: none;
  color: var(--gc, var(--primary));
  font-size: .85rem; font-weight: 700;
  cursor: pointer;
  display: flex; align-items: center; justify-content: center;
  flex-shrink: 0;
  transition: background .13s, transform .13s;
}
.group-lesson-open:hover { background: var(--gc, var(--primary)); color: #fff; transform: scale(1.1); }

.group-empty-msg {
  text-align: center; padding: 1rem 0 .5rem;
  color: var(--muted); font-size: .83rem;
}

/* Home page student */
@media (max-width: 768px) {
  #pageHome > div:first-of-type { grid-template-columns: 1fr !important; }
  #pageHome .overview-panel div[style*="grid-template-columns:repeat(3"] { grid-template-columns: 1fr !important; }
}

/* ===================== MOBILE FULL FIX ===================== */
@media (max-width: 768px) {

  /* Dashboard layout */
  .dash-main { margin-left: 0; }
  .menu-toggle { display: block; }
  .topbar { padding: 0 1rem; }

  /* Pages */
  .page { padding: 1rem; }
  .page-title { font-size: 1.25rem; }
  .page-header { flex-wrap: wrap; gap: .5rem; }

  /* Stat grid */
  .stat-grid { grid-template-columns: 1fr 1fr; gap: .75rem; }
  .stat-num { font-size: 1.5rem; }

  /* Overview grid */
  .overview-grid { grid-template-columns: 1fr; gap: 1rem; }

  /* Two col */
  .two-col { grid-template-columns: 1fr; }

  /* Tables — scroll ngang */
  .data-table { display: block; overflow-x: auto; white-space: nowrap; }
  .data-table th, .data-table td { padding: .6rem .75rem; font-size: .8rem; }

  /* Video grid */
  .video-grid { grid-template-columns: 1fr; }

  /* Group accordion */
  .group-card-grid { gap: .4rem; }
  .group-card-name { font-size: .88rem; }

  /* Filter bar */
  .filter-bar { gap: .5rem; }
  .filter-bar input, .filter-bar select { width: 100%; }

  /* Form panel */
  .form-panel { padding: 1rem; }

  /* Modal */
  .modal { padding: 1.25rem; border-radius: 16px; }

  /* Profile card */
  .profile-card { flex-direction: column; text-align: center; padding: 1.25rem; }

  /* Buttons */
  .btn-primary, .btn-outline { padding: .6rem 1rem; font-size: .85rem; }

  /* Auth */
  .auth-left { display: none; }
  .auth-right {
    padding: 1rem;
    align-items: flex-start;
    background: linear-gradient(145deg, #1a1a2e 0%, #16213e 45%, #0f3460 100%);
    min-height: 100vh;
  }
  .auth-box {
    padding: 1.75rem 1.25rem;
    border-radius: 18px;
    max-width: 100%;
    margin: auto;
    box-shadow: 0 8px 32px rgba(0,0,0,.18);
  }
  .auth-box-header h2 { font-size: 1.4rem; }
  .auth-wrap { min-height: 100vh; }
  body.auth-page { align-items: stretch; }

  /* Sidebar brand */
  .sidebar-brand { padding: 0 1rem; height: 56px; font-size: .9rem; }
  .sidebar-brand-text { font-size: .82rem; }

  /* Topbar avatar text — ẩn trên mobile nhỏ */
  .av-role { display: none; }
}

@media (max-width: 480px) {
  .stat-grid { grid-template-columns: 1fr 1fr; gap: .6rem; }
  .stat-card { padding: 1rem; gap: .75rem; }
  .stat-icon { font-size: 1.5rem; }
  .stat-num { font-size: 1.3rem; }
  .stat-label { font-size: .72rem; }

  /* Page home student — stack dọc */
  #pageHome > div[style*="grid-template-columns:1fr 1fr"] { grid-template-columns: 1fr !important; }
  #pageHome .overview-panel div[style*="repeat(3,1fr)"] { grid-template-columns: 1fr !important; }

  /* Group card header */
  .group-card-header { padding: .75rem .9rem; gap: .65rem; }
  .group-card-icon { width: 32px; height: 32px; font-size: .95rem; }
  .group-lesson-item { padding: .5rem .65rem; }

  /* Mini table scroll */
  .mini-table { display: block; overflow-x: auto; }

  /* Buttons full width trong form */
  .form-actions { flex-direction: column; }
  .form-actions .btn-primary,
  .form-actions .btn-outline { width: 100%; justify-content: center; }

  /* Page header stack */
  .page-header { flex-direction: column; align-items: flex-start; }
  .page-header > div { width: 100%; display: flex; gap: .5rem; flex-wrap: wrap; }
  .page-header .btn-primary,
  .page-header .btn-outline { flex: 1; justify-content: center; }
}

/* Sidebar backdrop mobile */
.sidebar-backdrop {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,.45);
  z-index: 199;
}
.sidebar-backdrop.show { display: block; }

/* Đóng sidebar khi click link trên mobile */
@media (max-width: 768px) {
  .sidebar.open { box-shadow: 4px 0 32px rgba(0,0,0,.3); }
}

/* Status pill */
.status-pill {
  display: inline-flex;
  align-items: center;
  gap: .25rem;
  padding: .2rem .65rem;
  border-radius: 20px;
  font-size: .75rem;
  font-weight: 700;
  white-space: nowrap;
}
.status-pill.green  { background: #d1fae5; color: #065f46; }
.status-pill.red    { background: #fee2e2; color: #991b1b; }
.status-pill.orange { background: #fef3c7; color: #92400e; }
.status-pill.gray   { background: #f1f5f9; color: #64748b; }

/* Student hero section */
#pageHome .page-title { color: #fff !important; }
@media (max-width: 768px) {
  #pageHome > div[style*="grid-template-columns:1fr 1fr"] { grid-template-columns: 1fr !important; }
  #pageHome > div[style*="repeat(3,1fr)"] { grid-template-columns: 1fr !important; }
}

@keyframes slideInRight {
  from { transform: translateX(120%); opacity: 0; }
  to   { transform: translateX(0);    opacity: 1; }
}


/* ===================== MOBILE OPTIMIZATION v2 ===================== */

/* --- Topbar --- */
@media (max-width: 768px) {
  .topbar {
    height: 54px;
    padding: 0 .85rem;
    gap: .5rem;
  }
  .av-name { font-size: .82rem; max-width: 110px; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
  .avatar { width: 34px; height: 34px; font-size: .72rem; }
}

/* --- Sidebar mobile --- */
@media (max-width: 768px) {
  .sidebar {
    width: 260px;
    overflow-y: auto;
    -webkit-overflow-scrolling: touch;
  }
  .sidebar-nav { padding: .5rem; gap: .1rem; }
  .slink { padding: .6rem .85rem; font-size: .85rem; }
  .slink-icon { font-size: .95rem; }
}

/* --- Pages --- */
@media (max-width: 768px) {
  .page { padding: .85rem .85rem 2rem; }
  .page-title { font-size: 1.15rem; margin-bottom: 1rem; }

  /* Page header buttons stack */
  .page-header {
    flex-direction: column;
    align-items: stretch;
    gap: .6rem;
  }
  .page-header .page-title { margin-bottom: 0; }
  .page-header > div,
  .page-header > button {
    width: 100%;
  }
  .page-header > div { display: flex; gap: .5rem; flex-wrap: wrap; }
  .page-header > div .btn-primary,
  .page-header > div .btn-outline { flex: 1; justify-content: center; min-width: 0; }
}

/* --- Stat cards --- */
@media (max-width: 480px) {
  .stat-card { padding: .85rem .9rem; gap: .6rem; border-radius: 12px; }
}

/* --- Data table mobile --- */
@media (max-width: 768px) {
  .data-table { font-size: .78rem; border-radius: 10px; }
  .data-table th, .data-table td { padding: .55rem .65rem; }
  /* Ẩn bớt cột ít quan trọng */
  .data-table th:nth-child(3),
  .data-table td:nth-child(3),
  .data-table th:nth-child(6),
  .data-table td:nth-child(6) { display: none; }
}

@media (max-width: 480px) {
  .data-table th:nth-child(4),
  .data-table td:nth-child(4) { display: none; }
}

/* --- Filter bar --- */
@media (max-width: 768px) {
  .filter-bar { flex-direction: column; gap: .5rem; }
  .filter-bar input,
  .filter-bar select { width: 100%; padding: .6rem .9rem; font-size: .88rem; }
}

/* --- Content rows --- */
@media (max-width: 480px) {
  .content-row { padding: .8rem 1rem; gap: .6rem; border-radius: 12px; }
  .row-actions { gap: .35rem; }
  .row-actions .btn-sm { padding: .25rem .55rem; font-size: .75rem; }
}

/* --- Video grid --- */
@media (max-width: 768px) {
  .video-grid { grid-template-columns: 1fr; gap: .85rem; }
  .video-thumb { height: 180px; }
}

/* --- Modal mobile --- */
@media (max-width: 768px) {
  .modal-overlay { padding: .5rem; align-items: flex-end; }
  .modal {
    border-radius: 20px 20px 0 0;
    max-height: 92vh;
    padding: 1.5rem 1.25rem 2rem;
    gap: .75rem;
  }
  .modal h2 { font-size: 1.05rem; }
  .modal input, .modal select, .modal textarea { padding: .6rem .85rem; font-size: .9rem; }
  .modal-actions { flex-direction: column-reverse; gap: .5rem; }
  .modal-actions .btn-primary,
  .modal-actions .btn-outline { width: 100%; justify-content: center; }

  /* Viewer modal full screen */
  .viewer-modal {
    width: 100vw !important;
    max-width: 100vw !important;
    height: 100dvh !important;
    max-height: 100dvh !important;
    border-radius: 0 !important;
    padding: .5rem !important;
  }
}

/* --- Overview panels --- */
@media (max-width: 768px) {
  .overview-panel { padding: 1rem; border-radius: 12px; }
  .panel-header { font-size: .88rem; }
}

/* --- Form panel --- */
@media (max-width: 768px) {
  .form-panel { padding: 1rem; border-radius: 12px; gap: .6rem; }
  .form-panel h3 { font-size: .95rem; }
  .form-panel input,
  .form-panel select,
  .form-panel textarea { padding: .6rem .85rem; font-size: .9rem; }
}

/* --- Mini table --- */
@media (max-width: 768px) {
  .mini-table { font-size: .78rem; }
  .mini-table th, .mini-table td { padding: .5rem .6rem; }
  /* Ẩn cột SĐT và Gmail trong mini table */
  .mini-table th:nth-child(3),
  .mini-table td:nth-child(3),
  .mini-table th:nth-child(4),
  .mini-table td:nth-child(4) { display: none; }
}

/* --- Group accordion mobile --- */
@media (max-width: 480px) {
  .group-card-header { padding: .7rem .85rem; gap: .6rem; }
  .group-card-icon { width: 30px; height: 30px; font-size: .9rem; border-radius: 8px; }
  .group-card-name { font-size: .85rem; }
  .group-lesson-item { padding: .5rem .6rem; gap: .55rem; }
  .group-lesson-title { font-size: .82rem; }
  .group-lesson-stats { font-size: .68rem; }
  .group-card-actions { opacity: 1; } /* Luôn hiện trên mobile */
  .group-lesson-item-actions { opacity: 1; }
}

/* --- Student page hero banner --- */
@media (max-width: 768px) {
  #heroBanner { padding: 1.25rem; border-radius: 14px; margin-bottom: 1rem; }
  #heroBanner h1.page-title { font-size: 1.2rem !important; }
  #homeAvatar { width: 52px !important; height: 52px !important; font-size: 1.3rem !important; }
}

@media (max-width: 480px) {
  #heroBanner { padding: 1rem; border-radius: 12px; }
  #heroBanner > div > div:first-child { gap: .85rem !important; margin-bottom: .85rem !important; }
  /* Quick stats wrap */
  #heroBanner > div > div:last-child { gap: .5rem !important; }
  #heroBanner > div > div:last-child > div { padding: .4rem .7rem !important; font-size: .72rem !important; }
}

/* --- Student home grid (lưu ý + hướng dẫn) --- */
@media (max-width: 600px) {
  /* Force stack dọc cho grid 1fr 1fr trong pageHome */
  #pageHome > div[style*="grid-template-columns:1fr 1fr"],
  #pageHome > div[style*="grid-template-columns: 1fr 1fr"] {
    grid-template-columns: 1fr !important;
  }
}

/* --- Profile page mobile --- */
@media (max-width: 768px) {
  /* Profile info grid 2 cột → 1 cột trên rất nhỏ */
  #pageProfile > div[style*="grid-template-columns:1fr 1fr"],
  #pageProfile > div[style*="grid-template-columns: 1fr 1fr"] {
    grid-template-columns: 1fr !important;
  }
}

@media (max-width: 480px) {
  /* Profile header */
  #pageProfile > div:first-child { padding: 1.25rem !important; border-radius: 14px !important; }
  #profileAvatar { width: 58px !important; height: 58px !important; font-size: 1.4rem !important; }
  #profileName { font-size: 1.1rem !important; }
}

/* --- Access stats / login history filter bar --- */
@media (max-width: 768px) {
  #pageAccessStats .page-header > div,
  #pageLoginHistory .page-header > div {
    flex-direction: column;
    width: 100%;
  }
  #pageAccessStats .page-header input[type="date"],
  #pageAccessStats .page-header select,
  #pageLoginHistory .page-header input[type="date"],
  #pageLoginHistory .page-header select {
    width: 100% !important;
    font-size: .85rem !important;
  }
  #pageAccessStats .page-header .btn-outline,
  #pageLoginHistory .page-header .btn-outline,
  #pageLoginHistory .page-header .btn-danger { width: 100%; justify-content: center; }

  /* Stat grid 3 cột → 1 cột */
  #accessStatGrid,
  #loginHistoryStats {
    grid-template-columns: 1fr !important;
  }
}

/* --- Announcements two-col --- */
@media (max-width: 768px) {
  #pageAnnouncements .two-col { grid-template-columns: 1fr; }
}

/* --- Buttons --- */
@media (max-width: 480px) {
  .btn-primary, .btn-outline { padding: .55rem .9rem; font-size: .82rem; border-radius: 9px; }
  .btn-sm { padding: .25rem .55rem; font-size: .75rem; }
}

/* --- Scrollbar sidebar --- */
.sidebar-nav::-webkit-scrollbar { width: 4px; }
.sidebar-nav::-webkit-scrollbar-track { background: transparent; }
.sidebar-nav::-webkit-scrollbar-thumb { background: rgba(255,255,255,.15); border-radius: 4px; }
.sidebar-nav::-webkit-scrollbar-thumb:hover { background: rgba(255,255,255,.3); }
.sidebar-nav { scrollbar-width: thin; scrollbar-color: rgba(255,255,255,.15) transparent; }

/* --- Scrollbar ẩn trên mobile --- */
@media (max-width: 768px) {
  .sidebar-nav::-webkit-scrollbar { display: none; }
  .sidebar-nav { scrollbar-width: none; }
  .modal::-webkit-scrollbar { width: 4px; }
  .modal::-webkit-scrollbar-thumb { background: var(--border); border-radius: 4px; }
}

/* --- Touch targets tối thiểu 44px --- */
@media (max-width: 768px) {
  .slink { min-height: 44px; }
  .btn-primary, .btn-outline { min-height: 40px; }
  .tab-btn { min-height: 40px; }
  .menu-toggle { min-width: 44px; min-height: 44px; display: flex; align-items: center; justify-content: center; }
}

/* --- Prevent horizontal overflow --- */
body { overflow-x: hidden; }
.dash-main { overflow-x: hidden; }
.page { overflow-x: hidden; }

/* --- Class grid mobile --- */
@media (max-width: 768px) {
  #classGrid { grid-template-columns: 1fr 1fr !important; gap: .75rem; }
}
@media (max-width: 480px) {
  #classGrid { grid-template-columns: 1fr !important; }
}

/* --- Lesson detail two-col --- */
@media (max-width: 768px) {
  #pageLessons .two-col { grid-template-columns: 1fr; gap: 1rem; }
}

/* --- Online student list wrap --- */
@media (max-width: 480px) {
  #onlineStudentList { gap: .35rem !important; }
}

/* --- Footer mobile --- */
@media (max-width: 768px) {
  footer { font-size: .7rem !important; padding: 1.25rem .85rem !important; line-height: 1.7 !important; }
}

/* ===================== AUTH MOBILE OPTIMIZE ===================== */
@media (max-width: 768px) {
  body.auth-page {
    background:
      radial-gradient(ellipse at 15% 15%, rgba(139,92,246,.5) 0%, transparent 45%),
      radial-gradient(ellipse at 85% 75%, rgba(6,182,212,.35) 0%, transparent 45%),
      radial-gradient(ellipse at 70% 20%, rgba(99,102,241,.3) 0%, transparent 40%),
      radial-gradient(ellipse at 30% 80%, rgba(236,72,153,.2) 0%, transparent 40%),
      linear-gradient(160deg, #060612 0%, #0d1225 50%, #0a1628 100%);
  }
  .auth-wrap { flex-direction: column; }
  .auth-right {
    flex: 1;
    padding: 1.25rem 1rem 2rem;
    background: transparent;
    justify-content: flex-start;
  }
  .auth-box {
    width: 100%;
    max-width: 480px;
    margin: 0 auto;
    padding: 1.75rem 1.25rem;
    border-radius: 24px;
    gap: .75rem;
    background: rgba(255,255,255,.96);
    backdrop-filter: blur(20px);
    box-shadow:
      0 24px 60px rgba(0,0,0,.4),
      0 0 0 1px rgba(255,255,255,.12),
      inset 0 1px 0 rgba(255,255,255,.8);
  }
  .auth-box-header h2 { font-size: 1.4rem; }
  .auth-box-header p { font-size: .82rem; }
  .tab-row { gap: .35rem; }
  .tab-btn { font-size: .82rem; padding: .5rem .75rem; }
  .input-icon input { font-size: .9rem; padding: .7rem .5rem .7rem 0; }
  .auth-row { font-size: .8rem; }
}

@media (max-width: 390px) {
  .auth-right { padding: 1rem .75rem 1.5rem; }
  .auth-box { padding: 1.5rem 1rem; border-radius: 18px; }
  .auth-box-header h2 { font-size: 1.25rem; }
  .input-icon span { padding: 0 .6rem; font-size: .9rem; }
  .input-icon input { font-size: .85rem; }
  .btn-primary.btn-block { font-size: .88rem; padding: .75rem; }
}

/* Online pulse */
@keyframes onlinePulse {
  0%, 100% { box-shadow: 0 0 0 3px rgba(16,185,129,.2); }
  50%       { box-shadow: 0 0 0 6px rgba(16,185,129,0); }
}

/* ── Student action dropdown menu ── */
.smenu-item {
  display: block;
  width: 100%;
  padding: .6rem 1rem;
  background: none;
  border: none;
  text-align: left;
  font-size: .85rem;
  cursor: pointer;
  color: var(--text);
  transition: background .15s;
  white-space: nowrap;
}
.smenu-item:hover { background: var(--primary-light); }
.smenu-item + .smenu-item { border-top: 1px solid var(--border); }

/* Desktop: ẩn nút ⋯ mờ khi không hover row */
@media (hover: hover) and (pointer: fine) {
  .smenu-toggle {
    opacity: 0.35;
    transition: opacity .15s;
  }
  tr:hover .smenu-toggle {
    opacity: 1;
  }
}
/* ===================== AUTH HOVER & ANIMATION ===================== */

/* Tab buttons */
.tab-btn {
  transition: background .2s, color .2s, transform .15s, box-shadow .2s;
}
.tab-btn:hover:not(.active) {
  background: rgba(99,102,241,.08);
  transform: translateY(-1px);
}
.tab-btn.active {
  box-shadow: 0 2px 8px rgba(99,102,241,.2);
}

/* Input icon — icon nhún nhẹ khi focus */
.input-icon:focus-within span {
  transform: scale(1.15);
  transition: transform .2s cubic-bezier(.34,1.56,.64,1);
  color: var(--primary);
}
.input-icon span {
  transition: transform .2s, color .2s;
}

/* Nút đăng nhập */
.btn-primary.btn-block {
  transition: transform .18s cubic-bezier(.34,1.56,.64,1), box-shadow .18s;
}
.btn-primary.btn-block:hover {
  transform: translateY(-2px) scale(1.01);
  box-shadow: 0 8px 24px rgba(99,102,241,.35);
}
.btn-primary.btn-block:active {
  transform: translateY(0) scale(.98);
}

/* Link hover */
.auth-hint a, #showGuideBtn, #forgotPwBtn {
  transition: color .15s, opacity .15s;
  position: relative;
}
.auth-hint a:hover, #showGuideBtn:hover, #forgotPwBtn:hover {
  opacity: .75;
}

/* Auth box — nhún nhẹ khi load */
.auth-box {
  animation: authBoxIn .5s cubic-bezier(.34,1.56,.64,1) both;
}
@keyframes authBoxIn {
  from { opacity: 0; transform: translateY(20px) scale(.97); }
  to   { opacity: 1; transform: translateY(0) scale(1); }
}

/* Logo mobile pop */
#mobileAuthHeader img {
  transition: transform .2s cubic-bezier(.34,1.56,.64,1);
}
#mobileAuthHeader img:hover {
  transform: scale(1.08) rotate(-3deg);
}

/* Feature items bên trái */
.auth-feature-item {
  transition: background .2s, transform .2s, box-shadow .2s;
}
.auth-feature-item:hover {
  transform: translateX(4px);
  box-shadow: 0 4px 16px rgba(0,0,0,.15);
}
.auth-feature-icon {
  transition: transform .2s cubic-bezier(.34,1.56,.64,1);
}
.auth-feature-item:hover .auth-feature-icon {
  transform: scale(1.15) rotate(-5deg);
}

/* Checkbox ghi nhớ */
.checkbox-label {
  transition: color .15s;
}
.checkbox-label:hover {
  color: var(--primary);
}

/* ===================== LOGIN BUTTON GLOW & GRADIENT ===================== */
#loginBtn {
  background: linear-gradient(135deg, #6366f1 0%, #8b5cf6 50%, #4f46e5 100%);
  background-size: 200% 200%;
  animation: gradientShift 4s ease infinite;
  box-shadow: 0 4px 20px rgba(99,102,241,.4);
  border: none;
}
#loginBtn:hover {
  box-shadow: 0 6px 28px rgba(99,102,241,.6), 0 0 0 4px rgba(99,102,241,.15);
  animation: gradientShift .8s ease infinite;
}
#loginBtn:active {
  transform: scale(.97);
  box-shadow: 0 2px 10px rgba(99,102,241,.3);
}
#loginBtn.loading {
  pointer-events: none;
  opacity: .85;
}
@keyframes gradientShift {
  0%   { background-position: 0% 50%; }
  50%  { background-position: 100% 50%; }
  100% { background-position: 0% 50%; }
}
@keyframes spin {
  to { transform: rotate(360deg); }
}

/* Glow effect trên input khi focus */
.input-icon:focus-within {
  box-shadow: 0 0 0 3px rgba(99,102,241,.15), 0 2px 12px rgba(99,102,241,.1);
}

/* ══════════════════════════════════════════
   MOBILE ADMIN OPTIMIZATIONS
   ══════════════════════════════════════════ */
@media (max-width: 768px) {

  /* ── Sidebar ── */
  .sidebar { width: 80vw; max-width: 260px; }
  .sidebar-backdrop { transition: opacity .25s; }
  .sidebar-backdrop.show { opacity: 1; }

  /* ── Topbar ── */
  .topbar { padding: 0 .75rem; gap: .4rem; height: 52px; }

  /* Ẩn search input, thay bằng icon */
  .topbar > div[style*="flex:1"],
  .topbar > div[style*="flex: 1"] {
    display: none !important;
  }

  /* Topbar right gọn lại */
  .topbar-right { gap: .35rem; }
  #darkModeBtn, #maintenanceBtn {
    width: 32px !important; height: 32px !important;
    font-size: .95rem !important;
  }
  .av-name { max-width: 80px; font-size: .78rem; }

  /* ── Page content ── */
  .page { padding: .75rem .75rem 1rem; }
  .page-header { flex-direction: column; align-items: flex-start; gap: .5rem; }
  .page-title { font-size: 1.1rem; }

  /* ── Toolbar nút ── */
  .page-header .btn-primary,
  .page-header .btn-outline,
  .page-header button {
    font-size: .8rem;
    padding: .42rem .75rem;
  }

  /* ── Filter bar ── */
  .filter-bar { flex-wrap: wrap; gap: .4rem; }
  .filter-bar select,
  .filter-bar input { font-size: .82rem; padding: .42rem .65rem; }

  /* ── Stats grid ── */
  .stat-grid { grid-template-columns: 1fr 1fr; gap: .5rem; }
  .stat-card { padding: .75rem; }
  .stat-num { font-size: 1.4rem; }
  .stat-label { font-size: .72rem; }

  /* ── Tables ── */
  .data-table { font-size: .78rem; }
  .data-table th, .data-table td { padding: .45rem .55rem; }

  /* ── Class cards (lớp học) ── */
  .class-grid { grid-template-columns: 1fr !important; }

  /* ── Modal ── */
  .modal { padding: 1.25rem 1rem; border-radius: 16px; margin: .5rem; }
  .modal h2 { font-size: .95rem; }
  .modal-actions { flex-wrap: wrap; }
  .modal-actions button { flex: 1; min-width: 0; }

  /* ── Form ── */
  .form-row, .two-col { grid-template-columns: 1fr !important; }
  .form-panel { padding: 1rem; }

  /* ── classDetailView table ── */
  #classDetailView { overflow-x: auto; -webkit-overflow-scrolling: touch; }
  #classDetailView table { min-width: 480px; }

  /* ── Toolbar nút học sinh (nhiều nút) ── */
  #pageStudents .page-header { align-items: stretch; }
  #pageStudents .page-header > div { flex-wrap: wrap; gap: .4rem; }
  #pageStudents .page-header button,
  #pageStudents .page-header select { font-size: .78rem; }
  #genMissingCodesBtn, #syncExpiryBtn, #syncClassNameBtn { display: none; }

  /* ── Overview greeting ── */
  .greeting-banner { padding: .85rem 1rem !important; }
  .greeting-banner .greeting-text { font-size: 1rem !important; }
  .greeting-banner .greeting-time { font-size: .75rem !important; }

  /* ── Announcement / Schedule cards ── */
  .ann-card, .schedule-card { padding: .75rem; }

  /* ── Competition / stats ── */
  .competition-table { display: block; overflow-x: auto; }

  /* ── Bottom padding for copyright bar ── */
  .dash-main { padding-bottom: 1.5rem; }
}

@media (max-width: 480px) {
  .stat-grid { grid-template-columns: 1fr 1fr; }
  .stat-num { font-size: 1.2rem; }

  /* Ẩn cột thứ 4 trở đi trong bảng học sinh */
  .data-table th:nth-child(n+5),
  .data-table td:nth-child(n+5) { display: none; }

  /* Nút trong page-header full width */
  .page-header { gap: .4rem; }

  /* Modal full screen gần như */
  .modal { margin: .25rem; max-height: 95vh; }

  .topbar { height: 48px; }
  .av-name { display: none; }
}

/* ── Mobile search bar (dưới topbar) ── */
#mobileSearchBar {
  display: none;
  position: fixed;
  top: 52px; left: 0; right: 0;
  background: var(--card);
  padding: .5rem .75rem;
  border-bottom: 1px solid var(--border);
  z-index: 998;
  box-shadow: 0 4px 12px rgba(0,0,0,.08);
}
#mobileSearchBar.open { display: block; }
#mobileSearchBar input {
  width: 100%; box-sizing: border-box;
  padding: .5rem 1rem .5rem 2rem;
  border: 1.5px solid var(--border);
  border-radius: 10px; outline: none;
  font-size: .88rem;
  background: var(--bg); color: var(--text);
}
#mobileSearchBar .search-icon {
  position: absolute; left: 1.25rem; top: 50%;
  transform: translateY(-50%);
  color: var(--muted); pointer-events: none;
}

@media (max-width: 768px) {
  #mobileSearchBtn { display: flex !important; }
  #globalSearchWrap { display: none !important; }
}

/* ── Fix form-actions thêm học viên trên mobile ── */
@media (max-width: 768px) {
  .form-actions {
    display: flex;
    flex-direction: column;
    gap: .5rem;
  }
  .form-actions button {
    width: 100%;
    text-align: center;
    white-space: normal;
    word-break: break-word;
  }
  #pageCreateStudent .two-col {
    grid-template-columns: 1fr !important;
  }
  #pageCreateStudent .form-panel {
    padding: .85rem;
  }
}

/* ══════════════════════════════════════════
   FLUID RESPONSIVE — co giãn mọi kích thước
   ══════════════════════════════════════════ */

/* Base: đảm bảo không element nào vượt container */
*, *::before, *::after { max-width: 100%; }
img, video, canvas { max-width: 100%; height: auto; }

/* Sidebar co khi cửa sổ nhỏ */
@media (max-width: 900px) and (min-width: 769px) {
  .sidebar { width: 200px; }
  .sidebar-brand-text { font-size: .82rem; }
  .slink-label { font-size: .82rem; }
}

/* Form actions luôn responsive */
.form-actions {
  display: flex;
  flex-wrap: wrap;
  gap: .5rem;
}
.form-actions button {
  flex: 1 1 auto;
  min-width: 120px;
  white-space: nowrap;
}

/* Stat grid fluid */
.stat-grid {
  grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
}

/* Two-col fluid */
.two-col {
  grid-template-columns: minmax(0, 380px) minmax(0, 1fr);
}
@media (max-width: 700px) {
  .two-col { grid-template-columns: 1fr; }
}

/* Topbar search co lại khi cửa sổ nhỏ */
#globalSearchWrap {
  min-width: 0;
  flex-shrink: 1;
}
#globalSearch {
  min-width: 0;
  width: 100%;
}

/* Modal luôn fit màn hình */
.modal-overlay, .overlay {
  padding: .75rem;
  align-items: flex-start;
  overflow-y: auto;
}
.modal, .modal-box {
  width: 100%;
  max-height: calc(100vh - 1.5rem);
  overflow-y: auto;
}

/* Page header wrap tự động */
.page-header {
  flex-wrap: wrap;
}

/* Filter bar wrap */
.filter-bar {
  flex-wrap: wrap;
}

/* Bảng luôn scroll ngang thay vì tràn */
.data-table-wrap,
.tbl-wrap,
div[style*="overflow-x"] {
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
}

/* Class grid fluid */
.class-grid {
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
}

/* Overview grid fluid */
.overview-grid {
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
}

/* Buttons trong toolbar không bị cắt */
.page-header button,
.page-header .btn-primary,
.page-header .btn-outline {
  white-space: nowrap;
  flex-shrink: 0;
}

/* Group/lesson list fluid */
.group-list, .content-list {
  min-width: 0;
}

/* Topbar co khi < 600px */
@media (max-width: 600px) {
  .topbar { gap: .3rem; padding: 0 .5rem; }
  .av-role { display: none; }
  .av-name { max-width: 70px; font-size: .74rem; }
}

/* Ultra small < 400px */
@media (max-width: 400px) {
  .page { padding: .5rem; }
  .stat-grid { grid-template-columns: 1fr 1fr; }
  .page-title { font-size: 1rem; }
  .av-name { display: none; }
  #darkModeBtn, #maintenanceBtn { display: none !important; }
}

/* ══════════════════════════════════════════════════
   ADMIN MOBILE — Tối ưu toàn diện
   ══════════════════════════════════════════════════ */

/* ── Bottom nav bar cho admin mobile ── */
@media (max-width: 768px) {

  /* Thanh nav dưới cùng — truy cập nhanh 5 mục chính */
  #adminBottomNav {
    display: flex !important;
    position: fixed;
    bottom: 0; left: 0; right: 0;
    height: 58px;
    background: var(--card, #fff);
    border-top: 1.5px solid var(--border, #e2e8f0);
    z-index: 1000;
    box-shadow: 0 -4px 16px rgba(0,0,0,.08);
  }
  .dash-main { padding-bottom: 70px !important; }

  /* Bảng học sinh — giữ 3 cột quan trọng nhất */
  #pageStudents .data-table th:nth-child(1),
  #pageStudents .data-table td:nth-child(1) { display: none; } /* Mã HV — ẩn */
  #pageStudents .data-table th:nth-child(5),
  #pageStudents .data-table td:nth-child(5) { display: none; } /* Lớp — ẩn */
  #pageStudents .data-table th:nth-child(6),
  #pageStudents .data-table td:nth-child(6) { display: none; } /* Ngày tạo — ẩn */
  #pageStudents .data-table th:nth-child(7),
  #pageStudents .data-table td:nth-child(7) { display: none; } /* Hết hạn — ẩn */
  #pageStudents .data-table th:nth-child(9),
  #pageStudents .data-table td:nth-child(9) { display: none; } /* Học tập — ẩn */

  /* Bảng học sinh — wrapper scroll */
  #pageStudents > div[style*="overflow-x"] { border-radius: 12px; }

  /* Greeting banner admin — gọn hơn */
  #greetingBanner {
    padding: .85rem 1rem !important;
    border-radius: 12px !important;
  }
  #greetingText { font-size: 1rem !important; }
  #greetingDate { font-size: .72rem !important; }
  #greetingTime { font-size: 1.2rem !important; }

  /* Stat grid — 2x2 gọn */
  #pageOverview .stat-grid { grid-template-columns: 1fr 1fr; gap: .6rem; }
  .stat-card { border-radius: 12px !important; }

  /* Overview panels stack dọc */
  #pageOverview .overview-grid { grid-template-columns: 1fr; gap: .75rem; }

  /* Expiry reminder panel */
  #expiryReminderPanel { margin-top: .75rem; }

  /* Online students list gọn */
  #onlineStudentList { gap: .35rem; }

  /* Page header — nút nhỏ gọn, wrap */
  .page-header > div[style] {
    flex-wrap: wrap !important;
    gap: .4rem !important;
  }
  .page-header button[class*="btn"] {
    font-size: .78rem !important;
    padding: .4rem .7rem !important;
    border-radius: 8px !important;
  }

  /* Xuất Excel + Thêm học sinh nổi bật hơn */
  #exportStudentsBtn { order: 1; }
  #openAddStudentBtn { order: 0; }

  /* Filter bar học sinh */
  #studentSearch { width: 100% !important; }
  #studentFilterClass, #studentFilterExpiry {
    flex: 1;
    min-width: 0;
  }

  /* Form panel — thêm học viên */
  #pageCreateStudent h3 { font-size: .92rem; }
  #pageCreateStudent label { font-size: .78rem; }
  #pageCreateStudent input,
  #pageCreateStudent select,
  #pageCreateStudent textarea {
    font-size: .88rem !important;
    padding: .55rem .75rem !important;
  }

  /* Mini student table ẩn cột ít quan trọng */
  #miniStudentTable th:nth-child(3),
  #miniStudentTable td:nth-child(3),
  #miniStudentTable th:nth-child(7),
  #miniStudentTable td:nth-child(7) { display: none; }
  #miniStudentTable { font-size: .76rem; }

  /* Bảng lớp học */
  #pageClasses .stat-grid { grid-template-columns: repeat(auto-fill, minmax(140px, 1fr)); }

  /* Class detail table */
  #classStudentBody tr td:nth-child(3),
  #classStudentBody tr th:nth-child(3) { display: none; }

  /* Alerts / security log */
  #alertList .content-row,
  #deviceAlertList .content-row { padding: .65rem .75rem; }

  /* Access stats — ẩn biểu đồ phức tạp khi quá nhỏ */
  #pageAccessStats .overview-grid { grid-template-columns: 1fr; }

  /* Competition page */
  #pageCompetition .stat-grid { grid-template-columns: 1fr 1fr 1fr; }

  /* Login history */
  #pageLoginHistory .stat-grid { grid-template-columns: 1fr 1fr 1fr; }

  /* Schedule / announcements */
  #pageAnnouncements .two-col { grid-template-columns: 1fr; }
  #pageSchedule .two-col { grid-template-columns: 1fr; }

  /* Modal bottom sheet feel */
  .overlay { align-items: flex-end !important; padding: 0 !important; }
  .overlay > .modal {
    border-radius: 20px 20px 0 0 !important;
    margin: 0 !important;
    max-height: 92vh;
    width: 100%;
    overflow-y: auto;
  }

  /* Sidebar nav items to avoid thumb dead zone */
  .slink { min-height: 44px; }
}

@media (max-width: 480px) {

  /* Topbar rất gọn */
  .topbar { padding: 0 .5rem; gap: .3rem; }
  #darkModeBtn, #maintenanceBtn {
    width: 30px !important; height: 30px !important;
    font-size: .85rem !important;
  }

  /* Stat card rất gọn */
  .stat-card { padding: .65rem .55rem; gap: .5rem; }
  .stat-icon { font-size: 1.4rem; }
  .stat-num  { font-size: 1.15rem; }
  .stat-label { font-size: .68rem; }

  /* Page title */
  .page-title { font-size: 1rem; }
  .page { padding: .6rem .6rem 1rem; }

  /* Greeting banner ẩn time vì không đủ chỗ */
  #greetingTime { display: none !important; }

  /* Data table cực nhỏ */
  .data-table th, .data-table td { font-size: .74rem !important; padding: .4rem .4rem !important; }

  /* Form input */
  input, select, textarea { font-size: .88rem !important; }

  /* Modal */
  .modal { padding: 1rem .85rem; }
  .modal h2 { font-size: .9rem; }

  /* Filter bar full width */
  .filter-bar > * { width: 100% !important; min-width: 0 !important; }

  /* Competition stat 1 cột */
  #pageCompetition .stat-grid,
  #pageLoginHistory .stat-grid { grid-template-columns: 1fr 1fr !important; }
}

/* ── Admin bottom nav HTML (thêm vào body qua JS) ── */
#adminBottomNav {
  display: none; /* ẩn trên desktop */
}
#adminBottomNav a {
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 3px;
  text-decoration: none;
  color: var(--muted, #94a3b8);
  font-size: .6rem;
  font-weight: 600;
  padding: .35rem .25rem;
  border-radius: 0;
  transition: color .15s;
  cursor: pointer;
  background: none;
  border: none;
}
#adminBottomNav a.active,
#adminBottomNav a:active { color: var(--primary, #6366f1); }
#adminBottomNav a span.nav-icon { font-size: 1.3rem; line-height: 1; }

/* ============================================================
   LỊCH HỌC V2 — Schedule grid (học sinh)
   ============================================================ */

/* Grid 7 cột desktop */
.sched-student-grid {
  display: grid;
  grid-template-columns: repeat(7, 1fr);
  gap: .4rem;
}

/* Cột ngày */
.sched-day-col {
  min-width: 0;
  display: flex;
  flex-direction: column;
  gap: .3rem;
}
.sched-day-col.sched-day-empty { opacity: .45; }

/* Header ngày */
.sched-day-header {
  text-align: center;
  padding: .4rem .2rem;
  border-radius: 10px;
  border: 1.5px solid var(--border);
  background: var(--bg);
}
.sched-day-header.sched-day-today {
  background: var(--primary);
  border-color: var(--primary);
}
.sched-day-header.sched-day-today .sched-day-name,
.sched-day-header.sched-day-today .sched-day-date { color: #fff; }
.sched-day-header.sched-day-sun {
  background: #fef3c7;
  border-color: #f59e0b;
}
.sched-day-header.sched-day-sun .sched-day-name,
.sched-day-header.sched-day-sun .sched-day-date { color: #92400e; }
.sched-day-name { display: block; font-weight: 800; font-size: .78rem; color: var(--text); }
.sched-day-date { display: block; font-size: .67rem; color: var(--muted); margin-top: .1rem; }

/* Placeholder ngày trống */
.sched-no-slot {
  text-align: center;
  font-size: .75rem;
  color: var(--muted);
  padding: .75rem 0;
  border: 1.5px dashed var(--border);
  border-radius: 9px;
}

/* Slot card */
.sched-slots { display: flex; flex-direction: column; gap: .3rem; }
.sched-slot-card {
  border-radius: 10px;
  border: 1.5px solid var(--border);
  padding: .5rem .6rem;
  background: var(--card);
  font-size: .75rem;
  transition: box-shadow .2s;
  word-break: break-word;
}
.sched-slot-card:hover { box-shadow: 0 4px 14px rgba(0,0,0,.1); }

.sched-slot-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: .25rem;
  margin-bottom: .2rem;
}
.sched-slot-session { font-weight: 700; font-size: .75rem; }
.sched-slot-badge {
  font-size: .62rem;
  font-weight: 800;
  color: #fff;
  border-radius: 20px;
  padding: .1rem .45rem;
  white-space: nowrap;
  flex-shrink: 0;
}
.sched-slot-subject { font-weight: 800; font-size: .78rem; line-height: 1.3; margin-bottom: .2rem; }
.sched-slot-time    { font-size: .7rem; color: inherit; opacity: .75; }
.sched-slot-notes   { font-size: .68rem; font-style: italic; opacity: .7; margin-top: .2rem; }
.sched-zalo-tip     {
  margin-top: .35rem;
  font-size: .68rem;
  background: rgba(255,255,255,.5);
  border-radius: 6px;
  padding: .2rem .45rem;
  font-weight: 700;
  display: inline-block;
}

/* ---- Mobile: 1 cột (chỉ ngày có lịch) ---- */
@media (max-width: 768px) {
  .sched-student-grid {
    grid-template-columns: 1fr;
    gap: .6rem;
  }
  .sched-day-col.sched-day-empty { display: none; } /* ẩn ngày trống trên mobile */
  .sched-day-header { display: flex; align-items: center; gap: .5rem; text-align: left; padding: .45rem .75rem; }
  .sched-day-name { font-size: .85rem; }
  .sched-day-date { font-size: .75rem; margin-top: 0; }
  .sched-slots { flex-direction: row; flex-wrap: wrap; gap: .4rem; }
  .sched-slot-card { flex: 1 1 calc(50% - .4rem); min-width: 130px; }
}

@media (max-width: 480px) {
  .sched-slot-card { flex: 1 1 100%; min-width: 0; }
}

/* ---- Admin: bảng 7 cột ---- */
#schedWeekTable .sched-slot-card { font-size: .72rem; }

@media (max-width: 900px) {
  #schedWeekTable > div { grid-template-columns: repeat(4, 1fr); }
}
@media (max-width: 600px) {
  #schedWeekTable > div { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 400px) {
  #schedWeekTable > div { grid-template-columns: 1fr; }
}