:root {
  --background: 222 47% 7%;
  --foreground: 210 40% 96%;
  --primary: 174 84% 50%;
  --primary-foreground: 222 47% 8%;
  --secondary: 263 85% 68%;
  --secondary-foreground: 0 0% 100%;
  --muted: 219 22% 68%;
  --destructive: 0 84% 62%;
  --destructive-foreground: 0 0% 100%;
  --border: 220 24% 24%;
  --card: 222 42% 12%;
  --success: 145 70% 48%;
  --warning: 42 95% 58%;
  --radius-sm: 10px;
  --radius-md: 18px;
  --radius-lg: 28px;
  --shadow-sm: 0 8px 24px hsl(222 60% 3% / 0.22);
  --shadow-md: 0 18px 48px hsl(222 60% 3% / 0.35);
  --shadow-lg: 0 28px 80px hsl(222 60% 3% / 0.48);
  --transition-fast: 160ms ease;
  --transition-smooth: 320ms cubic-bezier(.2,.8,.2,1);
}

.dark { --background: 222 47% 7%; --foreground: 210 40% 96%; --card: 222 42% 12%; }

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  min-height: 100vh;
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  color: hsl(var(--foreground));
  background:
    radial-gradient(circle at top left, hsl(var(--primary) / .22), transparent 36rem),
    radial-gradient(circle at bottom right, hsl(var(--secondary) / .2), transparent 32rem),
    hsl(var(--background));
}

button, input, select, textarea { font: inherit; }
button { cursor: pointer; }

a { color: inherit; text-decoration: none; }

#root { display: flex; min-height: 100vh; }

.sidebar {
  width: 290px;
  padding: 24px;
  border-right: 1px solid hsl(var(--border));
  background: hsl(var(--card) / .72);
  backdrop-filter: blur(18px);
  position: sticky;
  top: 0;
  height: 100vh;
  display: flex;
  flex-direction: column;
  gap: 28px;
}

.brand { display: flex; align-items: center; gap: 14px; }
.brand img { width: 54px; height: 54px; filter: drop-shadow(0 0 18px hsl(var(--primary) / .35)); }
.brand h1 { margin: 0; font-size: 20px; letter-spacing: -.02em; }
.brand p { margin: 4px 0 0; color: hsl(var(--muted)); font-size: 12px; }

.nav { display: grid; gap: 10px; }
.nav-link {
  padding: 13px 15px;
  border-radius: var(--radius-sm);
  color: hsl(var(--muted));
  transition: var(--transition-smooth);
}
.nav-link:hover, .nav-link.active {
  color: hsl(var(--foreground));
  background: linear-gradient(135deg, hsl(var(--primary) / .16), hsl(var(--secondary) / .14));
  transform: translateX(4px);
}

.sidebar-card {
  margin-top: auto;
  padding: 16px;
  border: 1px solid hsl(var(--primary) / .25);
  border-radius: var(--radius-md);
  background: hsl(var(--primary) / .08);
  display: grid;
  gap: 6px;
  box-shadow: var(--shadow-sm);
}
.sidebar-card span { color: hsl(var(--muted)); font-size: 13px; line-height: 1.45; }

.main { flex: 1; padding: 26px; overflow: hidden; }
.topbar {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 18px;
  margin-bottom: 24px;
}
.topbar h2 { margin: 0; font-size: clamp(26px, 4vw, 44px); letter-spacing: -.04em; }
.topbar p, .muted { color: hsl(var(--muted)); margin: 8px 0 0; line-height: 1.55; }
.top-actions { display: flex; flex-wrap: wrap; gap: 10px; justify-content: flex-end; }

.btn {
  border: 0;
  border-radius: 999px;
  padding: 11px 16px;
  color: hsl(var(--foreground));
  background: hsl(var(--card));
  border: 1px solid hsl(var(--border));
  transition: var(--transition-smooth);
  box-shadow: var(--shadow-sm);
}
.btn:hover { transform: translateY(-2px); box-shadow: var(--shadow-md); }
.btn-primary { background: linear-gradient(135deg, hsl(var(--primary)), hsl(var(--secondary))); color: hsl(var(--primary-foreground)); border-color: transparent; font-weight: 800; }
.btn-secondary { background: hsl(var(--secondary) / .18); border-color: hsl(var(--secondary) / .32); }
.btn-outline { background: hsl(var(--card) / .55); }
.btn-danger { background: hsl(var(--destructive) / .16); border-color: hsl(var(--destructive) / .35); }
.full { width: 100%; }

.page-section { display: none; animation: rise .35s ease both; }
.active-section { display: block; }
@keyframes rise { from { opacity: 0; transform: translateY(12px); } to { opacity: 1; transform: translateY(0); } }

.grid { display: grid; gap: 18px; }
.two-col { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.stats-grid { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 16px; margin-bottom: 18px; }
.card, .stat-card {
  border: 1px solid hsl(var(--border));
  border-radius: var(--radius-lg);
  background: linear-gradient(145deg, hsl(var(--card) / .88), hsl(var(--card) / .55));
  backdrop-filter: blur(20px);
  box-shadow: var(--shadow-md);
}
.card { padding: 20px; }
.stat-card { padding: 20px; position: relative; overflow: hidden; }
.stat-card span { color: hsl(var(--muted)); font-size: 13px; }
.stat-card strong { display: block; margin-top: 8px; font-size: 34px; }
.glow-primary::after, .glow-secondary::after, .glow-warning::after, .glow-success::after { content: ""; position: absolute; inset: auto -20px -34px auto; width: 110px; height: 110px; border-radius: 50%; filter: blur(26px); opacity: .45; }
.glow-primary::after { background: hsl(var(--primary)); } .glow-secondary::after { background: hsl(var(--secondary)); } .glow-warning::after { background: hsl(var(--warning)); } .glow-success::after { background: hsl(var(--success)); }

.section-title { display: flex; justify-content: space-between; align-items: center; gap: 12px; margin-bottom: 16px; }
.section-title.wrap { align-items: flex-start; flex-wrap: wrap; }
.section-title h3 { margin: 0; font-size: 20px; }
.pill, .tooltip { display: inline-flex; align-items: center; justify-content: center; border-radius: 999px; background: hsl(var(--primary) / .12); color: hsl(var(--primary)); padding: 6px 10px; font-size: 12px; font-weight: 800; }
.pill.danger { background: hsl(var(--destructive) / .12); color: hsl(var(--destructive)); }
.tooltip { width: 28px; height: 28px; padding: 0; }

.form-grid { display: grid; gap: 13px; }
label { display: grid; gap: 7px; color: hsl(var(--muted)); font-size: 13px; }
input, select, textarea {
  width: 100%;
  color: hsl(var(--foreground));
  background: hsl(var(--background) / .45);
  border: 1px solid hsl(var(--border));
  border-radius: var(--radius-sm);
  padding: 12px;
  outline: none;
  transition: var(--transition-fast);
}
input:focus, select:focus, textarea:focus { border-color: hsl(var(--primary)); box-shadow: 0 0 0 4px hsl(var(--primary) / .12); }
textarea { min-height: 132px; resize: vertical; }
select[multiple] { min-height: 130px; }

.list { display: grid; gap: 10px; }
.list.compact { margin-top: 12px; }
.item {
  padding: 14px;
  border: 1px solid hsl(var(--border));
  border-radius: var(--radius-md);
  background: hsl(var(--background) / .32);
  display: flex;
  justify-content: space-between;
  gap: 12px;
  align-items: center;
}
.item small { color: hsl(var(--muted)); display: block; margin-top: 3px; }
.item-actions { display: flex; gap: 8px; flex-wrap: wrap; }
.icon-btn { border: 1px solid hsl(var(--border)); color: hsl(var(--foreground)); background: hsl(var(--card)); border-radius: 999px; padding: 7px 10px; }
.alert { border-color: hsl(var(--warning) / .38); background: hsl(var(--warning) / .1); }
.danger-text { color: hsl(var(--destructive)); font-weight: 800; }

.attendance-bars { display: grid; gap: 12px; }
.bar-row { display: grid; gap: 6px; }
.bar-meta { display: flex; justify-content: space-between; font-size: 13px; }
.bar { height: 10px; background: hsl(var(--background) / .6); border-radius: 999px; overflow: hidden; }
.bar-fill { height: 100%; border-radius: inherit; background: linear-gradient(90deg, hsl(var(--primary)), hsl(var(--secondary))); transition: width var(--transition-smooth); }
.bar-fill.low { background: linear-gradient(90deg, hsl(var(--destructive)), hsl(var(--warning))); }

.table-wrap { overflow-x: auto; }
table { width: 100%; border-collapse: separate; border-spacing: 0 10px; min-width: 720px; }
th { color: hsl(var(--muted)); text-align: left; font-size: 13px; padding: 10px; }
td { padding: 12px 10px; background: hsl(var(--background) / .42); border-top: 1px solid hsl(var(--border)); border-bottom: 1px solid hsl(var(--border)); vertical-align: top; }
td:first-child { border-left: 1px solid hsl(var(--border)); border-radius: 14px 0 0 14px; font-weight: 800; }
td:last-child { border-right: 1px solid hsl(var(--border)); border-radius: 0 14px 14px 0; }
.cell-subject { font-weight: 900; }
.cell-teacher { color: hsl(var(--muted)); font-size: 12px; margin-top: 4px; }
.replacement { color: hsl(var(--warning)); font-size: 12px; margin-top: 4px; font-weight: 800; }
.event-cell { background: hsl(var(--secondary) / .16); color: hsl(var(--secondary)); font-weight: 900; }
.free-cell { color: hsl(var(--muted)); }

.slot-controls { display: grid; grid-template-columns: 1fr 1fr auto; gap: 14px; align-items: end; }
.mt { margin-top: 18px; }
.empty { color: hsl(var(--muted)); padding: 18px; border: 1px dashed hsl(var(--border)); border-radius: var(--radius-md); text-align: center; }

@media (max-width: 960px) {
  #root { flex-direction: column; }
  .sidebar { position: static; width: 100%; height: auto; }
  .nav { grid-template-columns: repeat(5, 1fr); overflow-x: auto; }
  .nav-link { text-align: center; white-space: nowrap; }
  .topbar, .two-col, .slot-controls { grid-template-columns: 1fr; flex-direction: column; }
  .stats-grid { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 560px) {
  .main, .sidebar { padding: 16px; }
  .stats-grid { grid-template-columns: 1fr; }
  .nav { grid-template-columns: 1fr 1fr; }
  .top-actions { width: 100%; justify-content: stretch; }
  .top-actions .btn { flex: 1 1 100%; }
  .item { align-items: flex-start; flex-direction: column; }
}