:root {
  color-scheme: light;
  --bg: #f7f8fa;
  --surface: #ffffff;
  --text: #0b1220;
  --muted: #6b7280;
  --border: #d1d5db;
  --primary: #2563eb;
  --primary-contrast: #ffffff;
  --alert-stale: #f59e0b;
  --alert-fresh: #22c55e;
  --danger: #ef4444;
  --card-shadow: 0 2px 6px rgba(15, 23, 42, 0.08);
}

:root.dark {
  color-scheme: dark;
  --bg: #0b1220;
  --surface: #111c33;
  --text: #f3f4f6;
  --muted: #a5adbb;
  --border: #1f2a44;
  --primary: #60a5fa;
  --primary-contrast: #0b1220;
  --card-shadow: 0 4px 10px rgba(15, 23, 42, 0.4);
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: "Inter", "Segoe UI", system-ui, -apple-system, sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
}

button {
  font: inherit;
  border: none;
  border-radius: 8px;
  padding: 0.5rem 0.9rem;
  cursor: pointer;
  transition: background 0.2s ease, color 0.2s ease, border-color 0.2s ease;
}

button:disabled {
  opacity: 0.6;
  cursor: not-allowed;
}

button.primary {
  background: var(--primary);
  color: var(--primary-contrast);
}

button.ghost {
  background: transparent;
  border: 1px solid var(--border);
  color: var(--text);
}

button.tab {
  border-radius: 999px;
  padding-inline: 1.3rem;
}

button.tab.active {
  background: var(--primary);
  color: var(--primary-contrast);
  border-color: var(--primary);
}

.app-header {
  position: sticky;
  top: 0;
  z-index: 100;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.75rem 1.5rem;
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  box-shadow: 0 1px 3px rgba(15, 23, 42, 0.1);
}

.app-header .brand {
  font-weight: 700;
  font-size: 1.1rem;
}

.app-header .actions {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
}

main {
  padding: 1rem clamp(1rem, 2vw, 2.5rem) 3rem;
}

.controls {
  display: grid;
  gap: 1rem;
  grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
  background: var(--surface);
  padding: 1rem;
  border-radius: 16px;
  border: 1px solid var(--border);
  margin-bottom: 1.5rem;
}

.controls label {
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
  font-size: 0.9rem;
}

.controls input,
.controls select {
  font: inherit;
  padding: 0.45rem 0.6rem;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: var(--bg);
  color: var(--text);
}

.controls .toggle {
  flex-direction: row;
  align-items: center;
  gap: 0.5rem;
}

.controls .toggle input {
  width: auto;
}

.tabs {
  display: flex;
  gap: 0.5rem;
  margin-bottom: 1.5rem;
}

.view {
  display: none;
}

.view.active {
  display: block;
}

.alert {
  position: sticky;
  top: 60px;
  z-index: 90;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.75rem 1.5rem;
  border-radius: 0;
  border-bottom: 1px solid var(--border);
  gap: 1rem;
}

.alert.hidden {
  display: none;
}

.alert .alert-text {
  font-weight: 500;
}

.alert .alert-actions {
  display: flex;
  gap: 0.5rem;
}

.alert.stale {
  background: rgba(245, 158, 11, 0.15);
  border-color: rgba(245, 158, 11, 0.5);
}

.alert.fresh {
  background: rgba(34, 197, 94, 0.15);
  border-color: rgba(34, 197, 94, 0.5);
}

.week-grid {
  display: grid;
  grid-template-columns: 90px repeat(7, 1fr);
  border: 1px solid var(--border);
  border-radius: 16px;
  overflow: hidden;
  background: var(--surface);
}

.current-week-title {
  color: var(--primary);
}

.week-grid header {
  background: var(--surface);
  padding: 0.75rem;
  border-bottom: 1px solid var(--border);
  font-weight: 600;
  display: flex;
  align-items: center;
  justify-content: center;
}

.week-grid .day-header {
  border-left: 1px solid var(--border);
}

.week-grid .session-label {
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(37, 99, 235, 0.08);
  font-weight: 600;
}

.week-grid .cell {
  min-height: 120px;
  border-left: 1px solid var(--border);
  border-top: 1px solid var(--border);
  padding: 0.6rem;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  overflow: auto;
}

.class-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 0.6rem 0.75rem;
  display: grid;
  gap: 0.25rem;
  box-shadow: var(--card-shadow);
  transition: transform 0.15s ease, box-shadow 0.15s ease, border-color 0.15s ease;
}

.class-card:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 16px rgba(15, 23, 42, 0.15);
}

.class-card header {
  font-weight: 600;
}

.class-card small {
  color: var(--muted);
}

.class-card.clash {
  border-color: var(--danger);
}

.class-card.clash::after {
  content: "⚠";
  position: absolute;
}

.card-colorized {
  border-width: 2px;
}

.day-view {
  display: grid;
  gap: 1rem;
}

.day-session {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 1rem;
}

.day-session h3 {
  margin-top: 0;
}

.semester-accordion {
  display: grid;
  gap: 0.75rem;
}

.week-accordion {
  border: 1px solid var(--border);
  border-radius: 14px;
  background: var(--surface);
}

.week-accordion summary {
  cursor: pointer;
  padding: 0.9rem 1.1rem;
  font-weight: 600;
}

.week-accordion .mini-grid {
  display: grid;
  grid-template-columns: repeat(7, minmax(100px, 1fr));
  border-top: 1px solid var(--border);
}

.week-accordion .mini-grid div {
  padding: 0.7rem;
  border-left: 1px solid var(--border);
  border-top: 1px solid var(--border);
  display: grid;
  gap: 0.25rem;
}

.detail-panel {
  position: fixed;
  top: 0;
  right: -400px;
  width: min(400px, 90vw);
  height: 100vh;
  background: var(--surface);
  border-left: 1px solid var(--border);
  box-shadow: -4px 0 16px rgba(15, 23, 42, 0.15);
  transition: right 0.3s ease;
  z-index: 120;
  display: flex;
  flex-direction: column;
}

.detail-panel.open {
  right: 0;
}

.detail-panel .close-detail {
  align-self: flex-end;
  margin: 0.75rem;
}

.detail-panel .detail-content {
  padding: 0 1.5rem 2rem;
  overflow-y: auto;
}

.detail-panel h2 {
  margin-top: 0;
}

.detail-panel dl {
  display: grid;
  gap: 0.75rem;
}

.detail-panel dt {
  font-weight: 600;
}

.detail-panel dd {
  margin: 0;
}

.toast-container {
  position: fixed;
  bottom: 1.5rem;
  right: 1.5rem;
  display: grid;
  gap: 0.75rem;
  z-index: 150;
}

.toast {
  background: var(--surface);
  border: 1px solid var(--border);
  padding: 0.75rem 1rem;
  border-radius: 12px;
  box-shadow: var(--card-shadow);
  animation: slide-in 0.3s ease forwards;
}

.toast.fade-out {
  opacity: 0;
  transform: translateX(40px);
  transition: opacity 0.3s ease, transform 0.3s ease;
}

@keyframes slide-in {
  from {
    transform: translateX(40px);
    opacity: 0;
  }
  to {
    transform: translateX(0);
    opacity: 1;
  }
}

.drop-overlay {
  position: fixed;
  inset: 0;
  background: rgba(37, 99, 235, 0.1);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 200;
  backdrop-filter: blur(2px);
}

.drop-overlay.hidden {
  display: none;
}

.drop-message {
  background: var(--surface);
  padding: 1.5rem 2rem;
  border-radius: 16px;
  border: 2px dashed var(--primary);
  font-weight: 600;
}

@media (max-width: 900px) {
  .week-grid {
    grid-template-columns: 70px repeat(7, minmax(160px, 1fr));
    overflow-x: auto;
  }

  .controls {
    grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
  }
}

.print-only {
  display: none;
}

@media print {
  body {
    background: #fff;
  }

  header,
  .controls,
  .tabs,
  .detail-panel,
  .toast-container,
  #alertBar,
  #dropOverlay {
    display: none !important;
  }

  .view {
    display: none !important;
  }

  #viewWeek {
    display: block !important;
  }
}