/* ═══════════════════════════════════════════════════════════
   SNAKE GAME — STYLE SHEET
   Modern Google-inspired design with dark/light themes
   ═══════════════════════════════════════════════════════════ */

/* ── CSS Custom Properties (Design Tokens) ────────────────── */
:root {
  /* Palette */
  --clr-bg:           #0f1117;
  --clr-surface:      #1a1d27;
  --clr-surface-alt:  #23273a;
  --clr-border:       #2e3348;
  --clr-text:         #e8eaf0;
  --clr-text-muted:   #8b90a8;
  --clr-accent:       #4CAF50;
  --clr-accent-glow:  rgba(76, 175, 80, .25);
  --clr-danger:       #ef4444;
  --clr-food:         #FF5252;

  /* Grid */
  --grid-bg:          #161923;
  --grid-line:        rgba(255,255,255,.04);
  --grid-radius:      16px;

  /* Shadows */
  --shadow-sm:  0 2px  8px rgba(0,0,0,.25);
  --shadow-md:  0 8px 32px rgba(0,0,0,.35);
  --shadow-lg:  0 16px 48px rgba(0,0,0,.5);

  /* Typography */
  --font: 'Outfit', system-ui, -apple-system, sans-serif;

  /* Transitions */
  --ease: cubic-bezier(.4, 0, .2, 1);
}

/* Light Theme */
[data-theme="light"] {
  --clr-bg:           #f0f2f5;
  --clr-surface:      #ffffff;
  --clr-surface-alt:  #f7f8fa;
  --clr-border:       #e0e3ea;
  --clr-text:         #1a1d27;
  --clr-text-muted:   #6b7280;
  --clr-accent-glow:  rgba(76, 175, 80, .15);

  --grid-bg:          #e8eaef;
  --grid-line:        rgba(0,0,0,.05);

  --shadow-sm:  0 2px  8px rgba(0,0,0,.08);
  --shadow-md:  0 8px 24px rgba(0,0,0,.1);
  --shadow-lg:  0 16px 40px rgba(0,0,0,.15);
}

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

html, body {
  width: 100%;
  height: 100%;
  overflow: hidden;
}

body {
  font-family: var(--font);
  background: var(--clr-bg);
  color: var(--clr-text);
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background .4s var(--ease), color .4s var(--ease);
}

/* ── Background Canvas ──────────────────────────────────── */
#bg-canvas {
  position: fixed;
  inset: 0;
  width: 100%;
  height: 100%;
  z-index: 0;
  pointer-events: none;
}

/* ── Screens ─────────────────────────────────────────────── */
.screen {
  position: fixed;
  inset: 0;
  z-index: 10;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 20px;
  padding: 20px;
  opacity: 0;
  pointer-events: none;
  transition: opacity .4s var(--ease);
}

.screen.active {
  opacity: 1;
  pointer-events: all;
}

/* ── Screen Card (glass) ──────────────────────────────────── */
.screen-card {
  background: var(--clr-surface);
  border: 1px solid var(--clr-border);
  border-radius: 24px;
  padding: 36px 40px;
  max-width: 420px;
  width: 100%;
  box-shadow: var(--shadow-lg);
  backdrop-filter: blur(20px);
  display: flex;
  flex-direction: column;
  gap: 20px;
  animation: cardIn .5s var(--ease) both;
  max-height: 85vh;
  overflow-y: auto;
}

/* Scrollbar styling */
.screen-card::-webkit-scrollbar {
  width: 6px;
}

.screen-card::-webkit-scrollbar-track {
  background: transparent;
}

.screen-card::-webkit-scrollbar-thumb {
  background: var(--clr-border);
  border-radius: 3px;
}

@keyframes cardIn {
  from { transform: translateY(24px) scale(.96); opacity: 0; }
  to   { transform: translateY(0) scale(1); opacity: 1; }
}

/* ── Logo ─────────────────────────────────────────────────── */
.logo {
  text-align: center;
}

.logo-icon {
  font-size: 56px;
  display: block;
  margin-bottom: 8px;
  animation: bounce 2s infinite;
}

@keyframes bounce {
  0%, 100% { transform: translateY(0); }
  50%      { transform: translateY(-8px); }
}

.logo h1 {
  font-size: 2.4rem;
  font-weight: 800;
  letter-spacing: -1px;
  background: linear-gradient(135deg, var(--clr-accent), #81C784);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.tagline {
  color: var(--clr-text-muted);
  font-weight: 300;
  font-size: .95rem;
  margin-top: 2px;
}

/* ── Setting Groups ──────────────────────────────────────── */
.setting-group {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.setting-group.row {
  flex-direction: row;
  align-items: center;
  justify-content: space-between;
}

.setting-label {
  font-size: .82rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: .8px;
  color: var(--clr-text-muted);
}

/* ── Button Group ─────────────────────────────────────────── */
.btn-group {
  display: flex;
  gap: 6px;
}

.btn-group.small {
  gap: 4px;
}

.btn-option {
  flex: 1;
  padding: 10px 14px;
  border: 1px solid var(--clr-border);
  border-radius: 12px;
  background: var(--clr-surface-alt);
  color: var(--clr-text-muted);
  font-family: var(--font);
  font-size: .85rem;
  font-weight: 500;
  cursor: pointer;
  transition: all .25s var(--ease);
}

.btn-option:hover {
  border-color: var(--clr-accent);
  color: var(--clr-text);
}

.btn-option.active {
  background: var(--clr-accent);
  border-color: var(--clr-accent);
  color: #fff;
  box-shadow: 0 4px 16px var(--clr-accent-glow);
}

.btn-group.small .btn-option {
  padding: 8px 14px;
  font-size: 1rem;
}

/* ── Toggle Switch ─────────────────────────────────────────── */
.toggle-list {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.toggle {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 10px 14px;
  background: var(--clr-surface-alt);
  border: 1px solid var(--clr-border);
  border-radius: 12px;
  cursor: pointer;
  font-size: .88rem;
  font-weight: 400;
  transition: border-color .25s var(--ease);
  user-select: none;
}

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

.toggle.compact {
  padding: 0;
  background: none;
  border: none;
}

.toggle input { display: none; }

.toggle-slider {
  position: relative;
  width: 44px;
  height: 24px;
  background: var(--clr-border);
  border-radius: 12px;
  flex-shrink: 0;
  transition: background .25s var(--ease);
}

.toggle-slider::after {
  content: '';
  position: absolute;
  top: 3px;
  left: 3px;
  width: 18px;
  height: 18px;
  background: #fff;
  border-radius: 50%;
  transition: transform .25s var(--ease), box-shadow .25s var(--ease);
  box-shadow: 0 1px 4px rgba(0,0,0,.2);
}

.toggle input:checked + .toggle-slider {
  background: var(--clr-accent);
}

.toggle input:checked + .toggle-slider::after {
  transform: translateX(20px);
  box-shadow: 0 2px 8px var(--clr-accent-glow);
}

/* ── Range Slider ─────────────────────────────────────────── */
input[type="range"] {
  -webkit-appearance: none;
  appearance: none;
  width: 100%;
  height: 6px;
  background: var(--clr-border);
  border-radius: 3px;
  outline: none;
  cursor: pointer;
}

input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 20px;
  height: 20px;
  background: var(--clr-accent);
  border-radius: 50%;
  border: none;
  box-shadow: 0 2px 8px var(--clr-accent-glow);
  cursor: pointer;
  transition: transform .2s var(--ease);
}

input[type="range"]::-webkit-slider-thumb:hover {
  transform: scale(1.15);
}

/* ── Color Picker ─────────────────────────────────────────── */
.color-picker {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
}

.color-swatch {
  width: 32px;
  height: 32px;
  border-radius: 50%;
  border: 3px solid transparent;
  cursor: pointer;
  transition: all .2s var(--ease);
  outline: none;
}

.color-swatch:hover {
  transform: scale(1.15);
}

.color-swatch.active {
  border-color: var(--clr-text);
  box-shadow: 0 0 0 3px var(--clr-accent-glow);
  transform: scale(1.1);
}

/* ── Primary Button ───────────────────────────────────────── */
.btn-primary {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  padding: 14px 28px;
  background: linear-gradient(135deg, var(--clr-accent), #66BB6A);
  border: none;
  border-radius: 14px;
  color: #fff;
  font-family: var(--font);
  font-size: 1.05rem;
  font-weight: 700;
  cursor: pointer;
  box-shadow: 0 6px 24px var(--clr-accent-glow);
  transition: all .25s var(--ease);
  letter-spacing: .3px;
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 32px var(--clr-accent-glow);
}

.btn-primary:active {
  transform: translateY(0);
}

.btn-secondary {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 12px 24px;
  background: var(--clr-surface-alt);
  border: 1px solid var(--clr-border);
  border-radius: 14px;
  color: var(--clr-text-muted);
  font-family: var(--font);
  font-size: .92rem;
  font-weight: 500;
  cursor: pointer;
  transition: all .25s var(--ease);
}

.btn-secondary:hover {
  border-color: var(--clr-accent);
  color: var(--clr-text);
}

.hint {
  text-align: center;
  font-size: .78rem;
  color: var(--clr-text-muted);
  font-weight: 300;
}

kbd {
  display: inline-block;
  padding: 2px 8px;
  background: var(--clr-surface-alt);
  border: 1px solid var(--clr-border);
  border-radius: 6px;
  font-family: var(--font);
  font-size: .82rem;
  font-weight: 500;
}

/* ── HUD ──────────────────────────────────────────────────── */
#game-hud {
  position: fixed;
  top: 20px;
  left: 50%;
  transform: translateX(-50%);
  z-index: 20;
  display: flex;
  gap: 24px;
  padding: 10px 28px;
  background: var(--clr-surface);
  border: 1px solid var(--clr-border);
  border-radius: 16px;
  box-shadow: var(--shadow-md);
  backdrop-filter: blur(12px);
}

.hud-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 2px;
}

.hud-label {
  font-size: .7rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 1px;
  color: var(--clr-text-muted);
}

.hud-value {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--clr-text);
  min-width: 40px;
  text-align: center;
  transition: transform .15s var(--ease);
}

.hud-value.pop {
  animation: pop .3s var(--ease);
}

@keyframes pop {
  0%   { transform: scale(1); }
  50%  { transform: scale(1.3); color: var(--clr-accent); }
  100% { transform: scale(1); }
}

/* ── Game Canvas Wrapper ──────────────────────────────────── */
#game-canvas-wrapper {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 100%;
  height: 100%;
  padding: 80px 20px 20px;
}

#game-canvas {
  border-radius: var(--grid-radius);
  box-shadow: var(--shadow-lg);
  max-width: 100%;
  max-height: 100%;
  image-rendering: crisp-edges;
}

/* ── Overlays ─────────────────────────────────────────────── */
.overlay {
  position: fixed;
  inset: 0;
  z-index: 30;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(0,0,0,.5);
  backdrop-filter: blur(8px);
  transition: opacity .3s var(--ease);
}

.overlay.hidden {
  opacity: 0;
  pointer-events: none;
}

.overlay-card {
  background: var(--clr-surface);
  border: 1px solid var(--clr-border);
  border-radius: 24px;
  padding: 36px 40px;
  max-width: 360px;
  width: 90%;
  box-shadow: var(--shadow-lg);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 16px;
  text-align: center;
}

.overlay-card h2 {
  font-size: 1.8rem;
  font-weight: 700;
}

.overlay-card p {
  color: var(--clr-text-muted);
  font-size: .9rem;
}

/* ── Game Over ─────────────────────────────────────────────── */
.gameover-title {
  font-size: 2rem;
  font-weight: 800;
  color: var(--clr-danger);
}

.gameover-stats {
  display: flex;
  gap: 40px;
  justify-content: center;
}

.stat {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
}

.stat-label {
  font-size: .75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 1px;
  color: var(--clr-text-muted);
}

.stat-value {
  font-size: 2.2rem;
  font-weight: 800;
}

.gameover-badge {
  background: linear-gradient(135deg, #FFD700, #FFA000);
  color: #1a1d27;
  padding: 8px 20px;
  border-radius: 20px;
  font-weight: 700;
  font-size: .9rem;
  animation: badgePulse 1.5s infinite;
}

.gameover-badge.hidden {
  display: none;
}

@keyframes badgePulse {
  0%, 100% { box-shadow: 0 0 0 0 rgba(255, 215, 0, .4); }
  50%      { box-shadow: 0 0 0 10px rgba(255, 215, 0, 0); }
}

/* ── Leaderboard ──────────────────────────────────────────── */
.leaderboard-card {
  max-width: 420px;
}

.leaderboard-card h3 {
  font-size: 1.1rem;
  font-weight: 700;
  margin-bottom: 4px;
}

.leaderboard-card ol {
  list-style: none;
  counter-reset: rank;
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.leaderboard-card ol li {
  counter-increment: rank;
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 10px 14px;
  background: var(--clr-surface-alt);
  border: 1px solid var(--clr-border);
  border-radius: 12px;
  font-size: .88rem;
  font-weight: 500;
}

.leaderboard-card ol li::before {
  content: counter(rank);
  display: flex;
  align-items: center;
  justify-content: center;
  width: 28px;
  height: 28px;
  background: var(--clr-border);
  border-radius: 8px;
  font-size: .8rem;
  font-weight: 700;
  flex-shrink: 0;
}

.leaderboard-card ol li:first-child::before {
  background: linear-gradient(135deg, #FFD700, #FFA000);
  color: #1a1d27;
}

.leaderboard-card ol li:nth-child(2)::before {
  background: linear-gradient(135deg, #C0C0C0, #9E9E9E);
  color: #1a1d27;
}

.leaderboard-card ol li:nth-child(3)::before {
  background: linear-gradient(135deg, #CD7F32, #B8860B);
  color: #fff;
}

.lb-name {
  flex: 1;
}

.lb-score {
  font-weight: 700;
  color: var(--clr-accent);
}

/* ── Mobile Controls ──────────────────────────────────────── */
#mobile-controls {
  position: fixed;
  bottom: 20px;
  left: 50%;
  transform: translateX(-50%);
  z-index: 25;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
}

#mobile-controls.hidden {
  display: none;
}

.dpad-row {
  display: flex;
  gap: 4px;
}

.dpad-btn {
  width: 56px;
  height: 56px;
  border: 1px solid var(--clr-border);
  border-radius: 14px;
  background: var(--clr-surface);
  color: var(--clr-text);
  font-size: 1.2rem;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: var(--shadow-sm);
  transition: all .15s var(--ease);
  -webkit-tap-highlight-color: transparent;
  user-select: none;
}

.dpad-btn:active {
  background: var(--clr-accent);
  color: #fff;
  transform: scale(.92);
}

/* ── Responsive ───────────────────────────────────────────── */
@media (max-width: 500px) {
  .screen-card {
    padding: 24px 20px;
    border-radius: 20px;
    gap: 16px;
  }

  .logo h1 {
    font-size: 1.8rem;
  }

  .logo-icon {
    font-size: 40px;
  }

  .btn-option {
    padding: 8px 10px;
    font-size: .78rem;
  }

  #game-hud {
    padding: 8px 18px;
    gap: 16px;
  }

  .hud-value {
    font-size: 1.2rem;
  }

  #game-canvas-wrapper {
    padding: 70px 10px 140px;
  }

  .gameover-stats {
    gap: 24px;
  }

  .stat-value {
    font-size: 1.6rem;
  }
}

/* ── Utility ──────────────────────────────────────────────── */
.hidden {
  display: none !important;
}

/* Food eaten particle burst */
@keyframes particleBurst {
  0%   { transform: scale(0); opacity: 1; }
  100% { transform: scale(2); opacity: 0; }
}