/* ================================
   CSS Custom Properties (Design Tokens)
   ================================ */
:root {
  /* Colors */
  --color-bg: #0a0a1a;
  --color-bg-gradient: linear-gradient(135deg, #0a0a1a 0%, #1a1a3a 50%, #0a1a2a 100%);
  --color-surface: #151530;
  --color-surface-elevated: #1f1f45;

  --color-text: #ffffff;
  --color-text-muted: #a0a0c0;
  --color-text-dim: #606080;

  --color-primary: #ffd700;
  --color-primary-glow: rgba(255, 215, 0, 0.4);

  --color-danger: #ff4444;
  --color-danger-glow: rgba(255, 68, 68, 0.5);

  --color-success: #44ff88;
  --color-warning: #ffaa00;

  /* Rarity Colors */
  --color-common: #b0b0b0;
  --color-uncommon: #44dd44;
  --color-rare: #4488ff;
  --color-legendary: #ff44ff;

  /* Card Colors */
  --card-bg: linear-gradient(145deg, #1a1a3a 0%, #252550 100%);
  --card-border: #3a3a6a;
  --card-gold: linear-gradient(135deg, #ffd700 0%, #ffaa00 50%, #ffd700 100%);

  /* Spacing */
  --space-xs: 4px;
  --space-sm: 8px;
  --space-md: 16px;
  --space-lg: 24px;
  --space-xl: 32px;
  --space-2xl: 48px;

  /* Typography */
  --font-display: 'Russo One', sans-serif;
  --font-body: 'Nunito', sans-serif;

  --text-xs: clamp(0.625rem, 2vw, 0.75rem);
  --text-sm: clamp(0.75rem, 2.5vw, 0.875rem);
  --text-base: clamp(0.875rem, 3vw, 1rem);
  --text-lg: clamp(1rem, 3.5vw, 1.25rem);
  --text-xl: clamp(1.25rem, 4vw, 1.5rem);
  --text-2xl: clamp(1.5rem, 5vw, 2rem);
  --text-3xl: clamp(2rem, 6vw, 3rem);

  /* Borders & Radius */
  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 16px;
  --radius-xl: 24px;
  --radius-full: 9999px;

  /* Shadows */
  --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.3);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.4);
  --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.5);
  --shadow-glow: 0 0 20px var(--color-primary-glow);

  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-base: 250ms ease;
  --transition-slow: 400ms ease;

  /* Z-index layers */
  --z-base: 1;
  --z-card: 10;
  --z-nav: 100;
  --z-modal: 1000;
}

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

html {
  font-size: 16px;
  -webkit-tap-highlight-color: transparent;
}

body {
  font-family: var(--font-body);
  background: var(--color-bg-gradient);
  color: var(--color-text);
  min-height: 100vh;
  min-height: 100dvh;
  overflow-x: hidden;
  line-height: 1.5;
}

img {
  max-width: 100%;
  height: auto;
  display: block;
}

button {
  font-family: inherit;
  cursor: pointer;
  border: none;
  background: none;
  color: inherit;
}

/* ================================
   App Layout
   ================================ */
.app {
  display: flex;
  flex-direction: column;
  min-height: 100vh;
  min-height: 100dvh;
}

/* ================================
   Header
   ================================ */
.header {
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: var(--space-md) var(--space-lg);
  background: var(--color-surface);
  border-bottom: 2px solid var(--card-border);
  position: sticky;
  top: 0;
  z-index: var(--z-nav);
}

.header-top {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-md);
  width: 100%;
  margin-bottom: var(--space-sm);
}

.home-link {
  width: 40px;
  height: 40px;
  border-radius: var(--radius-full);
  background: var(--color-surface-elevated);
  color: var(--color-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all var(--transition-base);
  border: 2px solid var(--card-border);
  flex-shrink: 0;
  text-decoration: none;
}

.home-link:hover {
  background: var(--color-primary);
  color: #000;
  border-color: var(--color-primary);
}

.logo {
  font-family: var(--font-display);
  font-size: var(--text-2xl);
  color: var(--color-primary);
  text-shadow: 0 0 10px var(--color-primary-glow),
               0 2px 4px rgba(0, 0, 0, 0.5);
  letter-spacing: 2px;
}

/* ================================
   Audio Toggle
   ================================ */
.audio-toggle {
  width: 40px;
  height: 40px;
  border-radius: var(--radius-full);
  background: var(--color-surface-elevated);
  color: var(--color-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all var(--transition-base);
  border: 2px solid var(--card-border);
  flex-shrink: 0;
}

.audio-toggle:hover {
  background: var(--color-primary);
  color: #000;
  border-color: var(--color-primary);
}

.audio-toggle .audio-off {
  display: none;
}

.audio-toggle.muted {
  color: var(--color-text-dim);
  border-color: var(--color-text-dim);
}

.audio-toggle.muted:hover {
  background: var(--color-surface);
  color: var(--color-text-muted);
  border-color: var(--color-text-muted);
}

.audio-toggle.muted .audio-on {
  display: none;
}

.audio-toggle.muted .audio-off {
  display: block;
}

/* Deck switch link */
.deck-switch-link {
  font-family: var(--font-display);
  font-size: var(--text-xs);
  color: var(--color-text-muted);
  padding: 6px 14px;
  border-radius: var(--radius-full);
  background: var(--color-surface-elevated);
  border: 2px solid var(--card-border);
  text-decoration: none;
  white-space: nowrap;
  transition: all var(--transition-base);
  flex-shrink: 0;
}

.deck-switch-link:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
}

/* Dinosaur deck theming */
.dino-deck .logo {
  color: #44ff88;
  text-shadow: 0 0 10px rgba(68, 255, 136, 0.4),
               0 2px 4px rgba(0, 0, 0, 0.5);
}

.dino-deck .nav-btn.active {
  color: #44ff88;
  border-color: #44ff88;
  box-shadow: 0 0 8px rgba(68, 255, 136, 0.3);
}

.dino-deck .home-link {
  color: #44ff88;
}

.dino-deck .home-link:hover {
  background: #44ff88;
  color: #000;
  border-color: #44ff88;
}

.nav {
  display: flex;
  gap: var(--space-sm);
}

.nav-btn {
  padding: var(--space-sm) var(--space-lg);
  font-size: var(--text-sm);
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 1px;
  border-radius: var(--radius-full);
  background: var(--color-surface-elevated);
  color: var(--color-text-muted);
  transition: all var(--transition-base);
  border: 2px solid transparent;
}

.nav-btn:hover {
  background: var(--color-surface);
  color: var(--color-text);
  border-color: var(--card-border);
}

.nav-btn.active {
  background: var(--card-gold);
  color: #000;
  border-color: var(--color-primary);
  box-shadow: var(--shadow-glow);
}

/* ================================
   Main Content
   ================================ */
.main {
  flex: 1;
  display: flex;
  flex-direction: column;
  padding: var(--space-lg);
}

.mode {
  display: none;
  flex: 1;
  flex-direction: column;
  align-items: center;
}

.mode.active {
  display: flex;
}

/* ================================
   Discovery Mode
   ================================ */
.discover-mode {
  justify-content: center;
  overflow: hidden;
}

.card-carousel {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-md);
  width: 100%;
  max-width: 500px;
  margin: 0 auto;
  flex: 1;
  min-height: 0;
}

.carousel-btn {
  width: 48px;
  height: 48px;
  border-radius: var(--radius-full);
  background: var(--color-surface-elevated);
  color: var(--color-text);
  font-size: var(--text-xl);
  font-weight: bold;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all var(--transition-base);
  border: 2px solid var(--card-border);
  flex-shrink: 0;
}

.carousel-btn:hover {
  background: var(--color-primary);
  color: #000;
  border-color: var(--color-primary);
  transform: scale(1.1);
}

.carousel-btn:active {
  transform: scale(0.95);
}

.card-stage {
  perspective: 1000px;
  flex: 1;
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 0;
}

.card-counter {
  margin-top: var(--space-sm);
  font-size: var(--text-base);
  color: var(--color-text-muted);
  font-weight: 600;
  flex-shrink: 0;
}

/* ================================
   Guess Mode
   ================================ */
.guess-mode {
  gap: var(--space-sm);
  justify-content: center;
  overflow: hidden;
}

.guess-card-stage {
  perspective: 1000px;
  width: 100%;
  max-width: 320px;
  flex-shrink: 1;
  min-height: 0;
}

/* Let card fill the stage height instead of using fixed aspect-ratio */
.guess-card {
  aspect-ratio: auto;
  height: 100%;
}

.guess-card .card-inner {
  height: 100%;
}

.guess-card .card-front,
.guess-card .card-back {
  height: 100%;
}

.guess-card .card-photo-frame {
  height: 100%;
}

.guess-card .card-image-wrapper {
  flex: 1;
  min-height: 0;
}

.guess-prompt {
  font-family: var(--font-display);
  font-size: var(--text-lg);
  color: var(--color-primary);
  text-align: center;
  padding: var(--space-sm);
}

.guess-options {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--space-sm);
  width: 100%;
  max-width: 400px;
  flex-shrink: 0;
}

.guess-option {
  padding: 10px var(--space-md);
  font-size: var(--text-sm);
  font-weight: 700;
  border-radius: var(--radius-lg);
  background: var(--color-surface-elevated);
  border: 2px solid var(--card-border);
  transition: all var(--transition-base);
  text-align: center;
  min-height: 44px;
}

.guess-option:hover:not(:disabled) {
  background: var(--color-surface);
  border-color: var(--color-primary);
  transform: translateY(-2px);
}

.guess-option.correct {
  background: var(--color-success);
  color: #000;
  border-color: var(--color-success);
}

.guess-option.incorrect {
  background: var(--color-danger);
  border-color: var(--color-danger);
  opacity: 0.7;
}

.guess-option:disabled {
  cursor: not-allowed;
}

.guess-result {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-sm);
  font-size: var(--text-lg);
  font-weight: 700;
  min-height: 28px;
  opacity: 0;
  transition: opacity var(--transition-base);
  flex-shrink: 0;
}

.guess-result.show {
  opacity: 1;
}

.guess-result.correct .result-icon::before {
  content: "✓";
  color: var(--color-success);
}

.guess-result.incorrect .result-icon::before {
  content: "✗";
  color: var(--color-danger);
}

.guess-score {
  display: flex;
  gap: var(--space-lg);
  font-size: var(--text-base);
  color: var(--color-text-muted);
  flex-shrink: 0;
}

.score-value, .streak-value {
  color: var(--color-primary);
  font-weight: 700;
}

.next-guess-btn {
  padding: 10px var(--space-xl);
  font-size: var(--text-base);
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 1px;
  border-radius: var(--radius-full);
  background: var(--card-gold);
  color: #000;
  transition: all var(--transition-base);
  display: none;
  min-height: 44px;
  flex-shrink: 0;
}

.next-guess-btn.show {
  display: block;
}

.next-guess-btn:hover {
  transform: scale(1.05);
  box-shadow: var(--shadow-glow);
}

/* ================================
   Collection Mode
   ================================ */
.collection-mode {
  gap: var(--space-lg);
  align-items: stretch;
}

.collection-header {
  text-align: center;
}

.collection-header h2 {
  font-family: var(--font-display);
  font-size: var(--text-2xl);
  color: var(--color-primary);
  margin-bottom: var(--space-md);
}

.collection-progress {
  display: flex;
  align-items: center;
  gap: var(--space-md);
  justify-content: center;
}

.progress-bar {
  width: 200px;
  height: 12px;
  background: var(--color-surface-elevated);
  border-radius: var(--radius-full);
  overflow: hidden;
  border: 1px solid var(--card-border);
}

.progress-fill {
  height: 100%;
  background: var(--card-gold);
  border-radius: var(--radius-full);
  transition: width var(--transition-slow);
}

.progress-text {
  font-weight: 700;
  color: var(--color-text-muted);
}

/* ================================
   Collection Category Tabs
   ================================ */
.collection-tabs {
  display: flex;
  gap: var(--space-sm);
  justify-content: flex-start;
  flex-wrap: wrap;
  padding: var(--space-sm) 0;
  margin-bottom: var(--space-md);
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  scrollbar-width: none;
}

.collection-tabs::-webkit-scrollbar {
  display: none;
}

.collection-tab {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
  padding: var(--space-sm) var(--space-md);
  min-width: 70px;
  border-radius: var(--radius-lg);
  background: var(--color-surface-elevated);
  border: 2px solid transparent;
  transition: all var(--transition-base);
  flex-shrink: 0;
}

.collection-tab:hover {
  background: var(--color-surface);
  border-color: var(--card-border);
}

.collection-tab.active {
  background: var(--color-surface);
  border-color: var(--color-primary);
  box-shadow: 0 0 10px var(--color-primary-glow);
}

.tab-icon {
  font-size: 1.5rem;
}

.tab-name {
  font-size: var(--text-xs);
  font-weight: 600;
  color: var(--color-text-muted);
  white-space: nowrap;
}

.collection-tab.active .tab-name {
  color: var(--color-primary);
}

.tab-count {
  font-size: 10px;
  color: var(--color-text-dim);
  background: var(--color-surface-elevated);
  padding: 1px 6px;
  border-radius: var(--radius-full);
}

.collection-tab.active .tab-count {
  background: var(--color-primary);
  color: #000;
}

.collection-filters {
  display: flex;
  gap: var(--space-sm);
  justify-content: center;
  flex-wrap: wrap;
}

.filter-btn {
  padding: var(--space-xs) var(--space-md);
  font-size: var(--text-sm);
  font-weight: 600;
  border-radius: var(--radius-full);
  background: var(--color-surface-elevated);
  color: var(--color-text-muted);
  transition: all var(--transition-fast);
  border: 1px solid transparent;
}

.filter-btn:hover {
  color: var(--color-text);
}

.filter-btn.active {
  background: var(--color-primary);
  color: #000;
}

/* ================================
   Collection Search
   ================================ */
.collection-search {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  max-width: 400px;
  width: 100%;
  margin: var(--space-sm) auto 0;
  padding: var(--space-sm) var(--space-md);
  background: var(--color-surface-elevated);
  border: 2px solid var(--card-border);
  border-radius: var(--radius-full);
  transition: border-color var(--transition-base);
}

.collection-search:focus-within {
  border-color: var(--color-primary);
  box-shadow: 0 0 10px var(--color-primary-glow);
}

.search-icon {
  color: var(--color-text-dim);
  flex-shrink: 0;
}

.collection-search:focus-within .search-icon {
  color: var(--color-primary);
}

.search-input {
  flex: 1;
  background: none;
  border: none;
  outline: none;
  color: var(--color-text);
  font-family: var(--font-body);
  font-size: var(--text-sm);
  min-width: 0;
}

.search-input::placeholder {
  color: var(--color-text-dim);
}

.collection-no-results {
  grid-column: 1 / -1;
  text-align: center;
  padding: var(--space-2xl) var(--space-md);
  color: var(--color-text-dim);
  font-size: var(--text-base);
}

.collection-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
  gap: var(--space-md);
  width: 100%;
  max-width: 800px;
  margin: 0 auto;
}

.collection-card {
  aspect-ratio: 3/4;
  border-radius: var(--radius-lg);
  overflow: hidden;
  cursor: pointer;
  transition: all var(--transition-base);
  position: relative;
  border: 2px solid var(--card-border);
}

.collection-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
}

.collection-card.discovered {
  background: var(--color-surface-elevated);
}

.collection-card.undiscovered {
  background: var(--color-surface);
}

.undiscovered-placeholder {
  width: 100%;
  height: 70%;
  display: flex;
  align-items: center;
  justify-content: center;
  background: linear-gradient(145deg, #151530 0%, #0a0a1a 100%);
}

.mystery-mark {
  font-family: var(--font-display);
  font-size: 3rem;
  color: var(--color-text-dim);
  opacity: 0.5;
}

.rarity-indicator {
  position: absolute;
  bottom: 40px;
  right: 8px;
  width: 12px;
  height: 12px;
  border-radius: var(--radius-full);
  border: 2px solid var(--color-surface);
}

.rarity-indicator.common { background: var(--color-common); }
.rarity-indicator.uncommon { background: var(--color-uncommon); }
.rarity-indicator.rare { background: var(--color-rare); }
.rarity-indicator.legendary {
  background: var(--color-legendary);
  box-shadow: 0 0 8px var(--color-legendary);
}

.collection-card img {
  width: 100%;
  height: 70%;
  object-fit: cover;
}

.collection-card .card-mini-name {
  padding: var(--space-sm);
  font-size: var(--text-xs);
  font-weight: 700;
  text-align: center;
  background: var(--color-surface);
}

.collection-card.undiscovered .card-mini-name {
  color: var(--color-text-dim);
}

/* ================================
   Modal
   ================================ */
.modal {
  position: fixed;
  inset: 0;
  z-index: var(--z-modal);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: var(--space-lg);
  opacity: 0;
  visibility: hidden;
  transition: all var(--transition-base);
}

.modal.open {
  opacity: 1;
  visibility: visible;
}

.modal-backdrop {
  position: absolute;
  inset: 0;
  background: rgba(0, 0, 0, 0.8);
  backdrop-filter: blur(4px);
}

.modal-content {
  position: relative;
  max-width: 400px;
  width: 100%;
  transform: scale(0.9);
  transition: transform var(--transition-base);
}

.modal.open .modal-content {
  transform: scale(1);
}

.modal-close {
  position: absolute;
  top: 8px;
  right: 8px;
  width: 36px;
  height: 36px;
  border-radius: var(--radius-full);
  background: var(--color-surface-elevated);
  color: var(--color-text);
  font-size: var(--text-xl);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 1;
}

.modal-close:hover {
  background: var(--color-danger);
}

/* ================================
   Responsive Adjustments
   ================================ */

/* Mobile-first: fit guess mode on screen without scrolling */
@media (max-width: 767px) {
  .header {
    padding: var(--space-sm) var(--space-md);
  }

  .header-top {
    margin-bottom: 4px;
  }

  .logo {
    font-size: var(--text-lg);
  }

  .nav-btn {
    padding: 6px var(--space-md);
    font-size: var(--text-xs);
  }

  .main {
    padding: var(--space-sm) var(--space-sm);
  }

  /* Hide carousel arrows on mobile - swipe to navigate */
  .carousel-btn {
    display: none;
  }

  .card-carousel {
    gap: 0;
  }

  /* Maximize card on mobile */
  .discover-mode {
    height: calc(100dvh - 90px);
    max-height: calc(100dvh - 90px);
  }

  .discover-mode .card {
    max-width: 100%;
  }

  /* Make guess mode fill available viewport height */
  .guess-mode {
    height: calc(100dvh - 90px);
    max-height: calc(100dvh - 90px);
    padding-bottom: env(safe-area-inset-bottom, 0);
  }
}

@media (min-width: 768px) {
  .header {
    flex-direction: row;
    justify-content: space-between;
  }

  .header-top {
    margin-bottom: 0;
  }

  .collection-grid {
    grid-template-columns: repeat(auto-fill, minmax(160px, 1fr));
  }
}

@media (min-width: 1024px) {
  .main {
    padding: var(--space-xl);
  }

  .card-carousel {
    max-width: 600px;
  }

  .collection-grid {
    grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
    max-width: 1000px;
  }
}

/* ================================
   Spaced Repetition Badges
   ================================ */
.sr-badge {
  position: absolute;
  top: 8px;
  left: 8px;
  padding: 2px 6px;
  font-size: 10px;
  font-weight: 700;
  text-transform: uppercase;
  border-radius: var(--radius-sm);
  z-index: 2;
}

.sr-badge.sr-due {
  background: var(--color-danger);
  color: white;
  animation: sr-pulse 1.5s ease-in-out infinite;
}

.sr-badge.sr-learning {
  background: var(--color-warning);
  color: #000;
}

.sr-badge.sr-mastered {
  background: var(--color-success);
  color: #000;
}

@keyframes sr-pulse {
  0%, 100% {
    opacity: 1;
    transform: scale(1);
  }
  50% {
    opacity: 0.7;
    transform: scale(1.05);
  }
}

/* ================================
   SR Stats Display
   ================================ */
.sr-stats {
  display: flex;
  gap: var(--space-md);
  justify-content: center;
  flex-wrap: wrap;
  margin-top: var(--space-sm);
}

.sr-stat {
  padding: 4px 10px;
  font-size: var(--text-xs);
  font-weight: 600;
  border-radius: var(--radius-full);
  background: var(--color-surface-elevated);
}

.sr-stat.due {
  color: var(--color-danger);
}

.sr-stat.learning {
  color: var(--color-warning);
}

.sr-stat.mastered {
  color: var(--color-success);
}

/* ================================
   Audio Replay Button
   ================================ */
.audio-replay-btn {
  position: absolute;
  bottom: 8px;
  right: 8px;
  width: 32px;
  height: 32px;
  border-radius: var(--radius-full);
  background: var(--color-surface-elevated);
  color: var(--color-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all var(--transition-fast);
  border: 2px solid var(--card-border);
  opacity: 0.8;
  z-index: 5;
}

.audio-replay-btn:hover {
  opacity: 1;
  background: var(--color-primary);
  color: #000;
  transform: scale(1.1);
}

.audio-replay-btn:active {
  transform: scale(0.95);
}

.audio-replay-btn svg {
  width: 16px;
  height: 16px;
}

/* ================================
   Utility Classes
   ================================ */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  border: 0;
}

.hidden {
  display: none !important;
}