:root {
  --font-base: 'Inter', 'Segoe UI', system-ui, -apple-system, BlinkMacSystemFont, 'Helvetica Neue', Arial, sans-serif;
  --radius-xl: 24px;
  --radius-lg: 16px;
  --radius-md: 12px;
  --radius-pill: 999px;
}

/* Dark Mode (Default) */
:root,
[data-theme="dark"] {
  --color-bg: #0a0e27;
  --color-bg-gradient: linear-gradient(135deg, #0a0e27 0%, #1a1f3a 50%, #0f1729 100%);
  --color-surface: #1a1f3a;
  --color-surface-soft: #252b47;
  --color-surface-muted: #2d3454;
  --color-border: #3d4563;
  --color-border-strong: #4e5a7d;
  --color-text: #e2e8f0;
  --color-muted: #94a3b8;
  --color-primary: #8b5cf6;
  --color-primary-soft: #2d1b69;
  --color-accent: #06b6d4;
  --color-warm: #f59e0b;
  --color-success: #10b981;
  --shadow-lg: 0 30px 70px rgba(0, 0, 0, 0.5);
  --shadow-md: 0 18px 35px rgba(0, 0, 0, 0.4);
  --shadow-soft: 0 8px 24px rgba(0, 0, 0, 0.3);
}

/* Light Mode */
[data-theme="light"] {
  --color-bg: #f1f5f9;
  --color-bg-gradient: linear-gradient(135deg, #f1f5f9 0%, #e2e8f0 50%, #f8fafc 100%);
  --color-surface: #ffffff;
  --color-surface-soft: #f8fafc;
  --color-surface-muted: #e2e8f0;
  --color-border: #cbd5e1;
  --color-border-strong: #94a3b8;
  --color-text: #0f172a;
  --color-muted: #475569;
  --color-primary: #8b5cf6;
  --color-primary-soft: #f3e8ff;
  --color-accent: #06b6d4;
  --color-warm: #f59e0b;
  --color-success: #10b981;
  --shadow-lg: 0 30px 70px rgba(15, 23, 42, 0.15);
  --shadow-md: 0 18px 35px rgba(15, 23, 42, 0.12);
  --shadow-soft: 0 8px 24px rgba(15, 23, 42, 0.08);
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: var(--font-base);
  background: var(--color-bg);
  background-image: var(--color-bg-gradient);
  color: var(--color-text);
  line-height: 1.6;
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
  transition: background 0.3s ease, color 0.3s ease;
}

a {
  color: inherit;
}

a:not([class]) {
  text-decoration: underline;
  text-decoration-color: rgba(139, 92, 246, 0.5);
}

.page-shell {
  width: min(1200px, 100% - 32px);
  margin: 0 auto;
  padding: clamp(1.5rem, 2vw, 3rem) 0 4rem;
}

.surface-card {
  background: var(--color-surface);
  border-radius: var(--radius-xl);
  padding: clamp(1.75rem, 3vw, 3.5rem);
  box-shadow: var(--shadow-lg);
  border: 1px solid var(--color-border);
}

.subtle-card {
  background: var(--color-surface-soft);
  border-radius: var(--radius-lg);
  padding: clamp(1.25rem, 2vw, 2rem);
  border: 1px solid var(--color-border);
}

.section-heading {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  margin-bottom: 1.75rem;
}

.section-heading h1,
.section-heading h2 {
  margin: 0;
  font-weight: 700;
  color: var(--color-text);
}

.section-heading h1 {
  font-size: clamp(2rem, 4vw, 2.75rem);
}

.section-heading h2 {
  font-size: clamp(1.5rem, 3vw, 2rem);
}

.section-heading p {
  color: var(--color-muted);
  margin: 0;
  font-size: 1rem;
}

.button-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-bottom: 1.5rem;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.65rem 1.4rem;
  border-radius: var(--radius-pill);
  border: 1px solid transparent;
  font-weight: 600;
  font-size: 0.95rem;
  text-decoration: none;
  cursor: pointer;
  transition: transform 0.25s ease, box-shadow 0.25s ease, background 0.25s ease;
  background: var(--color-surface);
  color: var(--color-text);
  box-shadow: var(--shadow-soft);
}

.btn:hover {
  transform: translateY(-1px);
  box-shadow: 0 12px 24px rgba(37, 99, 235, 0.12);
}

.btn--primary {
  background: var(--color-primary);
  color: white;
  box-shadow: 0 12px 30px rgba(37, 99, 235, 0.35);
}

.btn--secondary {
  background: rgba(6, 182, 212, 0.15);
  color: var(--color-accent);
  border-color: rgba(6, 182, 212, 0.4);
}

.btn--ghost {
  background: rgba(255, 255, 255, 0.05);
  border-color: var(--color-border);
}

.btn--success {
  background: rgba(16, 185, 129, 0.15);
  color: var(--color-success);
  border-color: rgba(16, 185, 129, 0.4);
}

.input-control {
  width: 100%;
  position: relative;
}

.input-control input,
.input-control select,
.input-control textarea {
  width: 100%;
  padding: 0.85rem 1rem;
  border-radius: var(--radius-md);
  border: 1.5px solid var(--color-border);
  font-size: 1rem;
  background: var(--color-surface);
  transition: border 0.2s ease, box-shadow 0.2s ease;
}

.input-control input:focus,
.input-control select:focus,
.input-control textarea:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: 0 0 0 4px rgba(37, 99, 235, 0.12);
}

.search-input {
  border-radius: var(--radius-pill);
  padding: 0.85rem 1.5rem;
}

.stat-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(230px, 1fr));
  gap: 1rem;
}

.stat-card {
  background: var(--color-surface-soft);
  border-radius: var(--radius-lg);
  padding: 1.25rem;
  border: 1px solid var(--color-border);
  box-shadow: var(--shadow-soft);
}

.stat-card__value {
  font-size: 2rem;
  font-weight: 700;
  color: var(--color-primary);
}

.stat-card__label {
  font-size: 0.95rem;
  color: var(--color-muted);
}

.table-wrapper {
  background: var(--color-surface);
  border-radius: var(--radius-lg);
  border: 1px solid var(--color-border);
  overflow: hidden;
  box-shadow: var(--shadow-soft);
}

.table {
  width: 100%;
  border-collapse: collapse;
}

.table thead {
  background: var(--color-primary-soft);
}

.table th {
  text-align: left;
  padding: 0.9rem 1rem;
  font-size: 0.95rem;
  color: var(--color-text);
}

.table td {
  padding: 0.8rem 1rem;
  border-bottom: 1px solid var(--color-border);
  color: var(--color-text);
  font-size: 0.95rem;
}

.table tbody tr:hover {
  background: rgba(37, 99, 235, 0.03);
}

.chip {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.4rem 0.9rem;
  border-radius: var(--radius-pill);
  background: rgba(139, 92, 246, 0.15);
  color: var(--color-primary);
  font-weight: 600;
  font-size: 0.85rem;
  border: 1px solid rgba(139, 92, 246, 0.3);
}

.year-panel {
  border-radius: var(--radius-lg);
  border: 1px solid var(--color-border);
  margin-bottom: 1rem;
  overflow: hidden;
  background: var(--color-surface);
}

.year-panel__header {
  background: var(--color-surface-muted);
  padding: 0.9rem 1.2rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  cursor: pointer;
  font-weight: 600;
  color: var(--color-text);
}

.year-panel__header .collapse-icon {
  font-size: 0.9rem;
  color: var(--color-muted);
  transition: transform 0.2s ease;
}

.year-panel__header.is-collapsed .collapse-icon {
  transform: rotate(-90deg);
}

.year-panel__body {
  padding: 0.75rem 1rem 1rem;
}

.week-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
  gap: 0.75rem;
}

.week-chip {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 0.7rem 0.5rem;
  border-radius: var(--radius-md);
  border: 1px solid var(--color-border);
  text-decoration: none;
  color: var(--color-text);
  background: var(--color-surface-soft);
  font-weight: 600;
  transition: transform 0.2s ease, background 0.2s ease, box-shadow 0.2s ease, border-color 0.2s ease;
}

.week-chip:hover {
  transform: translateY(-2px);
  background: var(--color-primary);
  color: white;
  border-color: var(--color-primary);
  box-shadow: 0 8px 24px rgba(139, 92, 246, 0.4);
}

.week-grid.is-hidden {
  display: none;
}

.badge {
  padding: 0.35rem 0.85rem;
  border-radius: var(--radius-pill);
  font-size: 0.8rem;
  font-weight: 600;
  background: rgba(139, 92, 246, 0.15);
  color: var(--color-primary);
  border: 1px solid rgba(139, 92, 246, 0.3);
}

.card-divider {
  height: 1px;
  width: 100%;
  background: var(--color-border);
  opacity: 0.6;
  margin: 1.5rem 0;
}

.subtitle-text {
  color: var(--color-muted);
  font-size: 0.95rem;
}

/* Theme Toggle Button */
.theme-toggle {
  position: fixed;
  bottom: 2rem;
  right: 2rem;
  width: 56px;
  height: 56px;
  border-radius: 50%;
  background: var(--color-surface);
  border: 2px solid var(--color-border);
  box-shadow: var(--shadow-lg);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  transition: all 0.3s ease;
  z-index: 1000;
}

.theme-toggle:hover {
  transform: scale(1.1) rotate(15deg);
  box-shadow: 0 8px 32px rgba(139, 92, 246, 0.4);
  border-color: var(--color-primary);
}

.theme-toggle:active {
  transform: scale(0.95);
}

@media (max-width: 768px) {
  .button-row {
    flex-direction: column;
    align-items: stretch;
  }

  .week-grid {
    grid-template-columns: repeat(auto-fill, minmax(120px, 1fr));
  }

  .surface-card,
  .subtle-card {
    padding: 1.25rem;
  }

  .theme-toggle {
    bottom: 1.5rem;
    right: 1.5rem;
    width: 48px;
    height: 48px;
    font-size: 1.25rem;
  }
}