/* ============================================
   CSS Custom Properties (Design Tokens)
   ============================================ */
:root {
  /* Colors - Light theme */
  --color-bg: #f0f2f5;
  --color-surface: #ffffff;
  --color-text: #1a1a2e;
  --color-text-secondary: #64748b;
  --color-border: #e2e8f0;
  --color-shadow: rgba(0, 0, 0, 0.06);
  --color-shadow-hover: rgba(0, 0, 0, 0.12);
  --color-header-bg: rgba(255, 255, 255, 0.8);
  --color-input-bg: #f1f5f9;
  --color-footer-text: #94a3b8;
  --color-clock-text: #cbd5e1;

  /* Spacing */
  --space-xs: 0.25rem;
  --space-sm: 0.5rem;
  --space-md: 1rem;
  --space-lg: 1.5rem;
  --space-xl: 2rem;
  --space-2xl: 3rem;

  /* Border radius */
  --radius-sm: 0.5rem;
  --radius-md: 0.75rem;
  --radius-lg: 1rem;
  --radius-xl: 1.25rem;
  --radius-full: 9999px;

  /* Typography */
  --font-sans: 'Inter', system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', monospace;
  --text-xs: clamp(0.7rem, 0.8vw, 0.75rem);
  --text-sm: clamp(0.8rem, 1vw, 0.875rem);
  --text-base: clamp(0.9rem, 1.1vw, 1rem);
  --text-lg: clamp(1rem, 1.3vw, 1.125rem);
  --text-xl: clamp(1.1rem, 1.5vw, 1.25rem);
  --text-2xl: clamp(1.4rem, 2vw, 1.75rem);
  --text-3xl: clamp(1.8rem, 3vw, 2.5rem);

  /* Transitions */
  --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-base: 250ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-slow: 350ms cubic-bezier(0.4, 0, 0.2, 1);

  /* Grid */
  --grid-columns: repeat(auto-fill, minmax(min(100%, 320px), 1fr));

  /* Palette (defaults, overridden by JS) */
  --palette-accent: #6366f1;
  --palette-gradient: linear-gradient(135deg, #6366f1, #ec4899, #f59e0b);
  --palette-focus-color: #6366f1;
  --palette-focus-shadow: rgba(99, 102, 241, 0.15);
}

/* ============================================
   Dark Theme
   ============================================ */
[data-theme="dark"] {
  --color-bg: #0f172a;
  --color-surface: #1e293b;
  --color-text: #e2e8f0;
  --color-text-secondary: #94a3b8;
  --color-border: #334155;
  --color-shadow: rgba(0, 0, 0, 0.3);
  --color-shadow-hover: rgba(0, 0, 0, 0.5);
  --color-header-bg: rgba(15, 23, 42, 0.85);
  --color-input-bg: #0f172a;
  --color-footer-text: #475569;
  --color-clock-text: #1e293b;
}

/* ============================================
   Reset & Base
   ============================================ */
*,
*::before,
*::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-sans);
  background-color: var(--color-bg);
  color: var(--color-text);
  line-height: 1.6;
  min-height: 100dvh;
  transition: background-color var(--transition-base), color var(--transition-base);
}

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

/* ============================================
   Header
   ============================================ */
.header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--color-header-bg);
  backdrop-filter: blur(12px) saturate(180%);
  -webkit-backdrop-filter: blur(12px) saturate(180%);
  border-bottom: 1px solid var(--color-border);
  padding: var(--space-md) var(--space-xl);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-lg);
  flex-wrap: wrap;
}

.header__title {
  font-size: var(--text-2xl);
  font-weight: 800;
  letter-spacing: -0.02em;
  background: var(--palette-gradient);
  background-clip: text;
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  white-space: nowrap;
}

.header__controls {
  display: flex;
  align-items: center;
  gap: var(--space-md);
  flex: 1;
  max-width: 480px;
  justify-content: flex-end;
}

/* ============================================
   Search Box
   ============================================ */
.search-box {
  position: relative;
  flex: 1;
  max-width: 360px;
}

.search-box__icon {
  position: absolute;
  left: var(--space-md);
  top: 50%;
  translate: 0 -50%;
  width: 18px;
  height: 18px;
  color: var(--color-text-secondary);
  pointer-events: none;
}

.search-box__input {
  width: 100%;
  padding: var(--space-sm) var(--space-md) var(--space-sm) 2.75rem;
  border: 2px solid var(--color-border);
  border-radius: var(--radius-full);
  background: var(--color-input-bg);
  color: var(--color-text);
  font-family: var(--font-sans);
  font-size: var(--text-sm);
  outline: none;
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}

.search-box__input::placeholder {
  color: var(--color-text-secondary);
}

.search-box__input:focus {
  border-color: var(--palette-focus-color);
  box-shadow: 0 0 0 3px var(--palette-focus-shadow);
}

/* ============================================
   Theme Toggle
   ============================================ */
.theme-toggle {
  display: grid;
  place-items: center;
  width: 40px;
  height: 40px;
  border: 2px solid var(--color-border);
  border-radius: var(--radius-md);
  background: var(--color-input-bg);
  cursor: pointer;
  color: var(--color-text-secondary);
  transition: border-color var(--transition-fast), color var(--transition-fast), background-color var(--transition-fast);
  flex-shrink: 0;
}

.theme-toggle:hover {
  border-color: var(--palette-accent);
  color: var(--palette-accent);
}

.theme-toggle__icon {
  width: 20px;
  height: 20px;
  grid-area: 1 / 1;
  transition: opacity var(--transition-fast), rotate var(--transition-base);
}

.theme-toggle__icon--moon {
  opacity: 0;
  rotate: -90deg;
}

[data-theme="dark"] .theme-toggle__icon--sun {
  opacity: 0;
  rotate: 90deg;
}

[data-theme="dark"] .theme-toggle__icon--moon {
  opacity: 1;
  rotate: 0deg;
}

/* ============================================
   Palette Switcher
   ============================================ */
.palette-switcher {
  display: flex;
  align-items: center;
  gap: 6px;
}

.palette-btn {
  --dot-color: #6366f1;
  width: 22px;
  height: 22px;
  border-radius: var(--radius-full);
  border: 2px solid var(--color-border);
  background: var(--dot-color);
  cursor: pointer;
  padding: 0;
  transition: border-color var(--transition-fast), scale var(--transition-fast), box-shadow var(--transition-fast);
}

.palette-btn:hover {
  scale: 1.15;
}

.palette-btn--active {
  border-color: var(--color-text);
  box-shadow: 0 0 0 2px var(--color-bg), 0 0 0 4px var(--dot-color);
}

/* ============================================
   Grid Layout
   ============================================ */
.grid {
  display: grid;
  grid-template-columns: var(--grid-columns);
  gap: var(--space-lg);
  padding: var(--space-xl);
  max-width: 1600px;
  margin-inline: auto;
}

/* ============================================
   Card Component
   ============================================ */
.card {
  --card-color: #6366f1;
  background: var(--color-surface);
  border-radius: var(--radius-xl);
  border: 1px solid var(--color-border);
  overflow: hidden;
  box-shadow: 0 1px 3px var(--color-shadow);
  transition:
    translate var(--transition-base),
    box-shadow var(--transition-base),
    border-color var(--transition-base);
  container-type: inline-size;
}

.card:not(.card--dragging):not(.card--placeholder):hover {
  translate: 0 -2px;
  box-shadow: 0 8px 24px var(--color-shadow-hover);
  border-color: color-mix(in srgb, var(--card-color) 40%, var(--color-border));
}

.card--collapsed .card__header {
  padding-bottom: var(--space-lg);
}

.card__header {
  padding: var(--space-lg);
  padding-bottom: var(--space-sm);
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  cursor: pointer;
  user-select: none;
  -webkit-user-select: none;
  touch-action: manipulation;
}

.card__header:hover .card__title {
  color: var(--card-color);
}

.card__chevron {
  margin-left: auto;
  width: 18px;
  height: 18px;
  flex-shrink: 0;
  color: var(--color-text-secondary);
  transition: rotate var(--transition-base);
  display: grid;
  place-items: center;
}

.card__chevron svg {
  width: 100%;
  height: 100%;
}

.card--collapsed .card__chevron {
  rotate: -90deg;
}

.card__color-dot {
  width: 12px;
  height: 12px;
  border-radius: var(--radius-full);
  background: var(--card-color);
  box-shadow: 0 0 8px color-mix(in srgb, var(--card-color) 50%, transparent);
  flex-shrink: 0;
}

.card__title {
  font-size: var(--text-lg);
  font-weight: 700;
  letter-spacing: -0.01em;
  color: var(--color-text);
}

.card__links {
  list-style: none;
  padding: var(--space-sm) var(--space-lg) var(--space-lg);
  display: flex;
  flex-direction: column;
  gap: var(--space-xs);
  overflow: hidden;
  transition: grid-template-rows var(--transition-base), opacity var(--transition-base), padding var(--transition-base);
}

.card--collapsed .card__links {
  padding-top: 0;
  padding-bottom: 0;
  max-height: 0;
  opacity: 0;
}

.card:not(.card--collapsed) .card__links {
  max-height: 500px;
}

.card__link {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  padding: var(--space-sm) var(--space-md);
  border-radius: var(--radius-md);
  font-size: var(--text-sm);
  color: var(--color-text-secondary);
  transition:
    background-color var(--transition-fast),
    color var(--transition-fast),
    padding-left var(--transition-fast);
}

.card__link:hover {
  background: color-mix(in srgb, var(--card-color) 8%, transparent);
  color: var(--card-color);
  padding-left: calc(var(--space-md) + 4px);
}

.card__link-favicon {
  width: 18px;
  height: 18px;
  border-radius: 4px;
  flex-shrink: 0;
  object-fit: contain;
  background: var(--color-input-bg);
  padding: 1px;
}

.card__link-text {
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

/* Hidden state for search filtering */
.card--hidden {
  display: none;
}

.card__link--hidden {
  display: none;
}

/* Highlight for search matches */
.card__link--match {
  background: color-mix(in srgb, var(--card-color) 6%, transparent);
}

/* ============================================
   Drag & Drop
   ============================================ */
.card--dragging {
  position: fixed;
  z-index: 1000;
  rotate: 2deg;
  scale: 1.03;
  opacity: 0.9;
  box-shadow: 0 16px 48px var(--color-shadow-hover);
  pointer-events: none;
  transition: none;
  animation: none;
}

.card--placeholder {
  background: color-mix(in srgb, var(--palette-accent) 8%, transparent);
  border: 2px dashed var(--palette-accent);
  border-radius: var(--radius-xl);
  opacity: 0.5;
  animation: none;
}

/* ============================================
   Clock
   ============================================ */
.clock {
  position: fixed;
  bottom: var(--space-xl);
  right: var(--space-xl);
  font-size: var(--text-3xl);
  font-weight: 800;
  font-variant-numeric: tabular-nums;
  color: var(--color-clock-text);
  pointer-events: none;
  user-select: none;
  letter-spacing: -0.02em;
  z-index: 50;
}

/* ============================================
   Footer
   ============================================ */
.footer {
  text-align: center;
  padding: var(--space-lg) var(--space-xl) var(--space-2xl);
  color: var(--color-footer-text);
  font-size: var(--text-xs);
}

.footer code {
  font-family: var(--font-mono);
  background: var(--color-input-bg);
  padding: var(--space-xs) var(--space-sm);
  border-radius: var(--radius-sm);
  font-size: var(--text-xs);
  border: 1px solid var(--color-border);
}

.footer__link {
  text-decoration: none;
  transition: color var(--transition-fast);
}

.footer__link:hover {
  color: var(--palette-accent);
}

.footer__link:hover code {
  border-color: var(--palette-accent);
  color: var(--palette-accent);
}

/* ============================================
   Animations
   ============================================ */
@keyframes card-enter {
  from {
    opacity: 0;
    translate: 0 20px;
    scale: 0.97;
  }
  to {
    opacity: 1;
    translate: 0 0;
    scale: 1;
  }
}

.card {
  animation: card-enter var(--transition-slow) backwards;
}

.card:nth-child(1) { animation-delay: 0ms; }
.card:nth-child(2) { animation-delay: 60ms; }
.card:nth-child(3) { animation-delay: 120ms; }
.card:nth-child(4) { animation-delay: 180ms; }
.card:nth-child(5) { animation-delay: 240ms; }
.card:nth-child(6) { animation-delay: 300ms; }
.card:nth-child(7) { animation-delay: 360ms; }
.card:nth-child(8) { animation-delay: 420ms; }

/* ============================================
   Container Queries
   ============================================ */
@container (max-width: 250px) {
  .card__link {
    font-size: var(--text-xs);
    padding: var(--space-xs) var(--space-sm);
  }

  .card__link-favicon {
    width: 14px;
    height: 14px;
  }
}

/* ============================================
   Responsive
   ============================================ */
@media (max-width: 640px) {
  .header {
    padding: var(--space-md);
    flex-direction: column;
    align-items: stretch;
  }

  .header__title {
    text-align: center;
    font-size: var(--text-xl);
  }

  .header__controls {
    max-width: none;
    justify-content: stretch;
  }

  .search-box {
    max-width: none;
  }

  .grid {
    padding: var(--space-md);
    gap: var(--space-md);
  }

  .clock {
    font-size: var(--text-2xl);
    right: var(--space-md);
    bottom: var(--space-md);
  }
}

/* ============================================
   Reduced motion
   ============================================ */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}

/* ============================================
   Scrollbar
   ============================================ */
::-webkit-scrollbar {
  width: 8px;
}

::-webkit-scrollbar-track {
  background: transparent;
}

::-webkit-scrollbar-thumb {
  background: var(--color-border);
  border-radius: var(--radius-full);
}

::-webkit-scrollbar-thumb:hover {
  background: var(--color-text-secondary);
}