:root {
  color-scheme: light;
  --font-sans: "Inter", ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  --font-display: "Outfit", "Inter", ui-sans-serif, system-ui, sans-serif;

  --slate-50: hsl(210 40% 98%);
  --slate-100: hsl(210 40% 96%);
  --slate-200: hsl(214 32% 91%);
  --slate-300: hsl(213 27% 84%);
  --slate-400: hsl(215 20% 65%);
  --slate-500: hsl(215 16% 47%);
  --slate-600: hsl(215 19% 35%);
  --slate-700: hsl(215 25% 27%);
  --slate-800: hsl(217 33% 17%);
  --slate-900: hsl(222 47% 11%);
  --slate-950: hsl(229 84% 5%);

  --cyan-300: hsl(186 94% 82%);
  --cyan-400: hsl(187 92% 69%);
  --cyan-500: hsl(188 86% 53%);
  --cyan-600: hsl(191 91% 36%);

  --emerald-300: hsl(156 72% 67%);
  --emerald-400: hsl(158 74% 57%);
  --emerald-500: hsl(160 84% 39%);

  --indigo-400: hsl(234 89% 74%);
  --indigo-500: hsl(239 84% 67%);
  --violet-500: hsl(258 90% 66%);
  --pink-500: hsl(322 93% 61%);
  --amber-400: hsl(43 96% 56%);

  --neon-mint: #2fffd0;
  --neon-lime: #b8ff3d;
  --neon-violet: #9b5cff;
  --neon-pink: #ff4ecd;
  --neon-amber: #ffd166;

  --bg: hsl(210 40% 98%);
  --bg-soft: hsl(210 40% 96%);
  --text: hsl(222 47% 11%);
  --text-muted: hsl(215 16% 47%);
  --border: hsl(214 32% 91% / 0.78);

  --panel: hsl(0 0% 100% / 0.68);
  --panel-strong: hsl(0 0% 100% / 0.86);
  --panel-dark: hsl(218 51% 12% / 0.78);

  --shadow-sm: 0 8px 28px hsl(222 47% 11% / 0.08);
  --shadow-md: 0 18px 60px hsl(222 47% 11% / 0.13);
  --shadow-lg: 0 28px 100px hsl(222 47% 11% / 0.18);
  --shadow-glow: 0 0 54px hsl(169 100% 59% / 0.3);
  --shadow-violet: 0 0 64px hsl(258 90% 66% / 0.24);

  --radius-sm: 0.875rem;
  --radius-md: 1.25rem;
  --radius-lg: 1.75rem;
  --radius-xl: 2.25rem;

  --ease-out: cubic-bezier(0.16, 1, 0.3, 1);
  --ease-elastic: cubic-bezier(0.34, 1.56, 0.64, 1);
}

.dark {
  color-scheme: dark;
  --bg: hsl(216 64% 7%);
  --bg-soft: hsl(216 53% 10%);
  --text: hsl(210 40% 98%);
  --text-muted: hsl(215 20% 72%);
  --border: hsl(0 0% 100% / 0.12);
  --panel: hsl(216 48% 13% / 0.62);
  --panel-strong: hsl(216 48% 13% / 0.82);
  --shadow-sm: 0 10px 36px hsl(0 0% 0% / 0.26);
  --shadow-md: 0 22px 72px hsl(0 0% 0% / 0.36);
  --shadow-lg: 0 34px 120px hsl(0 0% 0% / 0.5);
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  font-family: var(--font-sans);
  text-rendering: geometricPrecision;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  scrollbar-gutter: stable;
}

body {
  min-width: 320px;
  background:
    radial-gradient(circle at 12% 8%, hsl(169 100% 59% / 0.18), transparent 34rem),
    radial-gradient(circle at 86% 14%, hsl(258 90% 66% / 0.14), transparent 36rem),
    radial-gradient(circle at 50% 100%, hsl(188 86% 53% / 0.1), transparent 42rem),
    var(--bg);
}

.dark body {
  background:
    radial-gradient(circle at 12% 8%, hsl(169 100% 59% / 0.12), transparent 34rem),
    radial-gradient(circle at 86% 14%, hsl(258 90% 66% / 0.14), transparent 38rem),
    radial-gradient(circle at 50% 100%, hsl(188 86% 53% / 0.1), transparent 44rem),
    hsl(216 64% 7%);
}

::selection {
  color: hsl(216 64% 7%);
  background: var(--neon-mint);
}

::-webkit-scrollbar {
  width: 12px;
  height: 12px;
}

::-webkit-scrollbar-track {
  background: hsl(210 40% 96%);
}

::-webkit-scrollbar-thumb {
  border: 3px solid hsl(210 40% 96%);
  border-radius: 999px;
  background: linear-gradient(180deg, var(--neon-mint), var(--violet-500));
}

::-webkit-scrollbar-thumb:hover {
  background: linear-gradient(180deg, var(--cyan-400), var(--neon-pink));
}

.dark ::-webkit-scrollbar-track {
  background: hsl(216 64% 7%);
}

.dark ::-webkit-scrollbar-thumb {
  border-color: hsl(216 64% 7%);
}

a,
button,
input,
select,
textarea {
  -webkit-tap-highlight-color: transparent;
}

a {
  text-underline-offset: 0.25em;
}

button,
[role="button"] {
  cursor: pointer;
}

button:disabled,
[aria-disabled="true"] {
  cursor: not-allowed;
  opacity: 0.55;
  filter: saturate(0.65);
}

:focus {
  outline: none;
}

:focus-visible {
  outline: 3px solid hsl(169 100% 59% / 0.95);
  outline-offset: 4px;
  box-shadow: 0 0 0 7px hsl(169 100% 59% / 0.16);
}

#app-shell {
  isolation: isolate;
  overflow: hidden;
}

#app-shell::before {
  content: "";
  position: fixed;
  inset: 0;
  z-index: -3;
  pointer-events: none;
  opacity: 0.55;
  background-image:
    linear-gradient(hsl(188 86% 53% / 0.07) 1px, transparent 1px),
    linear-gradient(90deg, hsl(188 86% 53% / 0.07) 1px, transparent 1px);
  background-size: 42px 42px;
  mask-image: radial-gradient(circle at center, black 0%, transparent 75%);
}

.dark #app-shell::before {
  opacity: 0.42;
  background-image:
    linear-gradient(hsl(169 100% 59% / 0.08) 1px, transparent 1px),
    linear-gradient(90deg, hsl(169 100% 59% / 0.08) 1px, transparent 1px);
}

#app-shell::after {
  content: "";
  position: fixed;
  inset: 0;
  z-index: -2;
  pointer-events: none;
  opacity: 0.08;
  mix-blend-mode: multiply;
  background:
    repeating-linear-gradient(
      0deg,
      hsl(222 47% 11% / 0.5) 0,
      hsl(222 47% 11% / 0.5) 1px,
      transparent 1px,
      transparent 5px
    );
}

.dark #app-shell::after {
  opacity: 0.1;
  mix-blend-mode: screen;
}

#ambient-orb-primary,
#ambient-orb-secondary {
  animation: orbFloat 12s var(--ease-in-out, ease-in-out) infinite alternate;
  will-change: transform;
}

#ambient-orb-secondary {
  animation-duration: 15s;
  animation-delay: -5s;
}

#site-header {
  box-shadow: 0 1px 0 hsl(0 0% 100% / 0.45), 0 18px 50px hsl(222 47% 11% / 0.06);
}

.dark #site-header {
  box-shadow: 0 1px 0 hsl(0 0% 100% / 0.08), 0 18px 60px hsl(0 0% 0% / 0.22);
}

#brand-mark {
  position: relative;
  overflow: hidden;
}

#brand-mark::before {
  content: "";
  position: absolute;
  inset: -40%;
  background: conic-gradient(from 180deg, transparent, var(--neon-mint), var(--neon-violet), transparent);
  animation: spin 4s linear infinite;
  opacity: 0.85;
}

#brand-mark::after {
  content: "";
  position: absolute;
  inset: 3px;
  border-radius: 1rem;
  background: hsl(222 47% 11%);
}

.dark #brand-mark::after {
  background: hsl(0 0% 100%);
}

#brand-mark > span {
  position: relative;
  z-index: 1;
  font-family: var(--font-display);
  font-weight: 900;
  text-shadow: 0 0 18px hsl(169 100% 59% / 0.7);
}

#brand-name {
  letter-spacing: -0.045em;
  background: linear-gradient(120deg, var(--slate-950), var(--cyan-600), var(--violet-500));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.dark #brand-name {
  background-image: linear-gradient(120deg, hsl(0 0% 100%), var(--neon-mint), hsl(258 100% 78%));
}

#brand-tagline {
  text-shadow: 0 0 18px hsl(169 100% 59% / 0.22);
}

#leaderboard-link,
#theme-toggle-button,
.button,
.btn,
.primary-button,
.secondary-button,
.control-button,
.difficulty-button,
[data-button],
button[class*="rounded"] {
  position: relative;
  overflow: hidden;
  transform: translateZ(0);
  transition:
    transform 260ms var(--ease-out),
    border-color 260ms var(--ease-out),
    background-color 260ms var(--ease-out),
    color 260ms var(--ease-out),
    box-shadow 260ms var(--ease-out),
    opacity 260ms var(--ease-out);
}

#leaderboard-link::before,
#theme-toggle-button::before,
.button::before,
.btn::before,
.primary-button::before,
.secondary-button::before,
.control-button::before,
.difficulty-button::before,
[data-button]::before {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  opacity: 0;
  background: linear-gradient(120deg, transparent 0%, hsl(0 0% 100% / 0.5) 42%, transparent 70%);
  transform: translateX(-130%);
  transition: opacity 220ms ease;
}

#leaderboard-link:hover::before,
#theme-toggle-button:hover::before,
.button:hover::before,
.btn:hover::before,
.primary-button:hover::before,
.secondary-button:hover::before,
.control-button:hover::before,
.difficulty-button:hover::before,
[data-button]:hover::before {
  opacity: 1;
  animation: shimmer 900ms var(--ease-out);
}

#theme-toggle-button:hover,
#leaderboard-link:hover {
  box-shadow: 0 14px 34px hsl(188 86% 53% / 0.16);
}

main,
#main-content {
  position: relative;
  z-index: 1;
}

section {
  scroll-margin-top: 7rem;
}

#hero-section,
.hero-section,
.hero {
  position: relative;
}

#hero-section h1,
.hero-title,
h1 {
  letter-spacing: -0.075em;
  line-height: 0.92;
}

#hero-section h1,
.hero-title {
  background:
    linear-gradient(110deg, var(--slate-950) 0%, hsl(188 86% 34%) 42%, hsl(258 90% 58%) 76%, var(--slate-950) 100%);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.dark #hero-section h1,
.dark .hero-title {
  background-image: linear-gradient(110deg, hsl(0 0% 100%) 0%, var(--neon-mint) 40%, hsl(258 100% 78%) 76%, hsl(0 0% 100%) 100%);
}

#game-section {
  position: relative;
}

.glass,
.panel,
.card,
.game-card,
.stat-card,
.settings-card,
#game-panel,
#stats-panel,
#controls-panel,
#settings-panel,
#leaderboard-panel,
#instructions-panel {
  position: relative;
  border: 1px solid var(--border);
  background:
    linear-gradient(135deg, hsl(0 0% 100% / 0.78), hsl(0 0% 100% / 0.45)),
    linear-gradient(180deg, hsl(169 100% 59% / 0.08), transparent);
  box-shadow: var(--shadow-md);
  backdrop-filter: blur(24px) saturate(1.25);
  -webkit-backdrop-filter: blur(24px) saturate(1.25);
}

.dark .glass,
.dark .panel,
.dark .card,
.dark .game-card,
.dark .stat-card,
.dark .settings-card,
.dark #game-panel,
.dark #stats-panel,
.dark #controls-panel,
.dark #settings-panel,
.dark #leaderboard-panel,
.dark #instructions-panel {
  border-color: hsl(0 0% 100% / 0.11);
  background:
    linear-gradient(135deg, hsl(216 48% 13% / 0.86), hsl(216 64% 7% / 0.68)),
    linear-gradient(180deg, hsl(169 100% 59% / 0.08), transparent);
  box-shadow: var(--shadow-lg);
}

.card::before,
.game-card::before,
#game-panel::before,
#stats-panel::before,
#controls-panel::before,
#settings-panel::before {
  content: "";
  position: absolute;
  inset: 0;
  border-radius: inherit;
  pointer-events: none;
  background:
    linear-gradient(135deg, hsl(0 0% 100% / 0.66), transparent 32%),
    radial-gradient(circle at top right, hsl(169 100% 59% / 0.14), transparent 34%);
  opacity: 0.85;
}

.dark .card::before,
.dark .game-card::before,
.dark #game-panel::before,
.dark #stats-panel::before,
.dark #controls-panel::before,
.dark #settings-panel::before {
  background:
    linear-gradient(135deg, hsl(0 0% 100% / 0.13), transparent 34%),
    radial-gradient(circle at top right, hsl(169 100% 59% / 0.16), transparent 36%);
}

.card > *,
.game-card > *,
#game-panel > *,
#stats-panel > *,
#controls-panel > *,
#settings-panel > * {
  position: relative;
  z-index: 1;
}

#game-board-wrapper,
.game-board-wrapper,
.canvas-shell,
#canvas-shell,
.board-shell {
  position: relative;
  overflow: hidden;
  border-radius: clamp(1.25rem, 3vw, 2rem);
  border: 1px solid hsl(188 86% 53% / 0.22);
  background:
    radial-gradient(circle at 18% 12%, hsl(169 100% 59% / 0.2), transparent 24%),
    radial-gradient(circle at 86% 78%, hsl(258 90% 66% / 0.18), transparent 32%),
    linear-gradient(135deg, hsl(216 55% 10%), hsl(214 58% 16%));
  box-shadow:
    inset 0 1px 0 hsl(0 0% 100% / 0.14),
    inset 0 -20px 80px hsl(0 0% 0% / 0.24),
    0 28px 90px hsl(188 86% 53% / 0.2),
    0 0 0 8px hsl(188 86% 53% / 0.035);
}

#game-board-wrapper::before,
.game-board-wrapper::before,
.canvas-shell::before,
#canvas-shell::before,
.board-shell::before {
  content: "";
  position: absolute;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  opacity: 0.42;
  background-image:
    linear-gradient(hsl(169 100% 59% / 0.13) 1px, transparent 1px),
    linear-gradient(90deg, hsl(169 100% 59% / 0.13) 1px, transparent 1px);
  background-size: 24px 24px;
  mask-image: radial-gradient(circle at center, black 0%, transparent 88%);
}

#game-board-wrapper::after,
.game-board-wrapper::after,
.canvas-shell::after,
#canvas-shell::after,
.board-shell::after {
  content: "";
  position: absolute;
  inset: 0;
  z-index: 2;
  pointer-events: none;
  border-radius: inherit;
  box-shadow:
    inset 0 0 0 1px hsl(0 0% 100% / 0.08),
    inset 0 0 52px hsl(169 100% 59% / 0.08);
}

canvas,
#game-canvas,
.game-canvas,
#snake-board,
.snake-board {
  position: relative;
  z-index: 1;
  display: block;
  width: 100%;
  max-width: 100%;
  aspect-ratio: 1 / 1;
  border-radius: clamp(1rem, 2.5vw, 1.65rem);
  image-rendering: pixelated;
  image-rendering: crisp-edges;
  background:
    radial-gradient(circle at 20% 15%, hsl(169 100% 59% / 0.11), transparent 24%),
    linear-gradient(135deg, hsl(217 53% 11%), hsl(216 60% 7%));
  box-shadow: inset 0 0 0 1px hsl(0 0% 100% / 0.08);
  touch-action: none;
}

.game-overlay,
#game-overlay,
#pause-overlay,
#game-over-overlay,
#start-overlay {
  position: absolute;
  inset: 0;
  z-index: 5;
  display: grid;
  place-items: center;
  padding: 1.25rem;
  border-radius: inherit;
  background:
    radial-gradient(circle at center, hsl(169 100% 59% / 0.12), transparent 38%),
    hsl(216 64% 7% / 0.62);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  animation: fadeIn 360ms var(--ease-out) both;
}

.game-overlay[hidden],
#game-overlay[hidden],
#pause-overlay[hidden],
#game-over-overlay[hidden],
#start-overlay[hidden],
.is-hidden,
.hidden-overlay {
  display: none !important;
}

.score-value,
#score-value,
#score,
#high-score,
#best-score,
.stat-value {
  font-family: var(--font-display);
  font-weight: 900;
  letter-spacing: -0.05em;
  font-variant-numeric: tabular-nums;
  background: linear-gradient(120deg, var(--slate-950), var(--cyan-600), var(--violet-500));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.dark .score-value,
.dark #score-value,
.dark #score,
.dark #high-score,
.dark #best-score,
.dark .stat-value {
  background-image: linear-gradient(120deg, hsl(0 0% 100%), var(--neon-mint), hsl(258 100% 78%));
  text-shadow: 0 0 32px hsl(169 100% 59% / 0.24);
}

.stat-label,
.label,
.kicker {
  color: var(--text-muted);
  font-weight: 800;
  letter-spacing: 0.16em;
  text-transform: uppercase;
}

.badge,
.pill,
.status-pill,
#game-status,
#difficulty-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  border: 1px solid hsl(188 86% 53% / 0.22);
  border-radius: 999px;
  background: hsl(0 0% 100% / 0.62);
  color: hsl(191 91% 30%);
  box-shadow: 0 10px 28px hsl(188 86% 53% / 0.09);
  backdrop-filter: blur(18px);
  -webkit-backdrop-filter: blur(18px);
}

.badge::before,
.pill::before,
.status-pill::before,
#game-status::before {
  content: "";
  width: 0.5rem;
  height: 0.5rem;
  flex: 0 0 auto;
  border-radius: 999px;
  background: var(--neon-mint);
  box-shadow: 0 0 16px hsl(169 100% 59% / 0.82);
  animation: pulseDot 1.8s ease-in-out infinite;
}

.dark .badge,
.dark .pill,
.dark .status-pill,
.dark #game-status,
.dark #difficulty-badge {
  border-color: hsl(169 100% 59% / 0.2);
  background: hsl(0 0% 100% / 0.06);
  color: var(--neon-mint);
}

.primary-button,
#start-button,
#restart-button,
#play-button,
#resume-button,
button[data-variant="primary"] {
  border: 1px solid hsl(169 100% 59% / 0.36);
  background:
    radial-gradient(circle at top left, hsl(0 0% 100% / 0.32), transparent 34%),
    linear-gradient(135deg, hsl(169 100% 59%), hsl(188 86% 53%) 52%, hsl(258 90% 66%));
  color: hsl(216 64% 7%);
  box-shadow:
    0 18px 42px hsl(188 86% 53% / 0.28),
    0 0 0 6px hsl(169 100% 59% / 0.08);
  font-weight: 900;
}

.primary-button:hover,
#start-button:hover,
#restart-button:hover,
#play-button:hover,
#resume-button:hover,
button[data-variant="primary"]:hover {
  transform: translateY(-3px) scale(1.015);
  box-shadow:
    0 26px 62px hsl(188 86% 53% / 0.34),
    0 0 0 8px hsl(169 100% 59% / 0.1);
}

.primary-button:active,
#start-button:active,
#restart-button:active,
#play-button:active,
#resume-button:active {
  transform: translateY(-1px) scale(0.99);
}

.secondary-button,
#pause-button,
#reset-button,
#mute-button,
button[data-variant="secondary"] {
  border: 1px solid var(--border);
  background:
    linear-gradient(135deg, hsl(0 0% 100% / 0.78), hsl(0 0% 100% / 0.46));
  color: var(--text);
  box-shadow: var(--shadow-sm);
  font-weight: 850;
  backdrop-filter: blur(18px);
  -webkit-backdrop-filter: blur(18px);
}

.dark .secondary-button,
.dark #pause-button,
.dark #reset-button,
.dark #mute-button,
.dark button[data-variant="secondary"] {
  background: linear-gradient(135deg, hsl(0 0% 100% / 0.1), hsl(0 0% 100% / 0.045));
  color: hsl(210 40% 98%);
}

.secondary-button:hover,
#pause-button:hover,
#reset-button:hover,
#mute-button:hover,
button[data-variant="secondary"]:hover {
  transform: translateY(-2px);
  border-color: hsl(169 100% 59% / 0.42);
  box-shadow: 0 16px 42px hsl(188 86% 53% / 0.15);
}

.control-pad,
#control-pad,
.mobile-controls {
  user-select: none;
  -webkit-user-select: none;
}

.control-button,
.direction-button,
.mobile-control-button,
[data-direction] {
  display: inline-grid;
  place-items: center;
  min-width: 3rem;
  min-height: 3rem;
  border: 1px solid var(--border);
  border-radius: 1rem;
  background:
    linear-gradient(135deg, hsl(0 0% 100% / 0.82), hsl(0 0% 100% / 0.5));
  color: var(--text);
  box-shadow:
    0 12px 30px hsl(222 47% 11% / 0.1),
    inset 0 1px 0 hsl(0 0% 100% / 0.5);
  font-weight: 900;
  backdrop-filter: blur(18px);
  -webkit-backdrop-filter: blur(18px);
}

.dark .control-button,
.dark .direction-button,
.dark .mobile-control-button,
.dark [data-direction] {
  background:
    linear-gradient(135deg, hsl(0 0% 100% / 0.12), hsl(0 0% 100% / 0.045));
  box-shadow:
    0 16px 34px hsl(0 0% 0% / 0.28),
    inset 0 1px 0 hsl(0 0% 100% / 0.08);
}

.control-button:hover,
.direction-button:hover,
.mobile-control-button:hover,
[data-direction]:hover,
.control-button.is-active,
.direction-button.is-active,
.mobile-control-button.is-active,
[data-direction].is-active {
  transform: translateY(-2px) scale(1.03);
  border-color: hsl(169 100% 59% / 0.48);
  color: hsl(188 86% 36%);
  box-shadow:
    0 18px 46px hsl(188 86% 53% / 0.2),
    0 0 0 6px hsl(169 100% 59% / 0.08);
}

.dark .control-button:hover,
.dark .direction-button:hover,
.dark .mobile-control-button:hover,
.dark [data-direction]:hover,
.dark .control-button.is-active,
.dark .direction-button.is-active,
.dark .mobile-control-button.is-active,
.dark [data-direction].is-active {
  color: var(--neon-mint);
}

.difficulty-group,
.segmented-control,
.tabs {
  display: inline-flex;
  gap: 0.35rem;
  padding: 0.35rem;
  border: 1px solid var(--border);
  border-radius: 999px;
  background: hsl(0 0% 100% / 0.54);
  box-shadow: var(--shadow-sm);
  backdrop-filter: blur(18px);
  -webkit-backdrop-filter: blur(18px);
}

.dark .difficulty-group,
.dark .segmented-control,
.dark .tabs {
  background: hsl(0 0% 100% / 0.055);
}

.difficulty-button,
.tab-button,
.segment-button {
  border-radius: 999px;
  padding: 0.65rem 1rem;
  color: var(--text-muted);
  font-weight: 850;
  letter-spacing: -0.01em;
}

.difficulty-button:hover,
.tab-button:hover,
.segment-button:hover {
  color: var(--text);
  background: hsl(0 0% 100% / 0.58);
}

.dark .difficulty-button:hover,
.dark .tab-button:hover,
.dark .segment-button:hover {
  background: hsl(0 0% 100% / 0.08);
}

.difficulty-button.is-active,
.difficulty-button[aria-pressed="true"],
.tab-button.is-active,
.tab-button[aria-selected="true"],
.segment-button.is-active {
  color: hsl(216 64% 7%);
  background: linear-gradient(135deg, var(--neon-mint), var(--cyan-400));
  box-shadow: 0 10px 26px hsl(169 100% 59% / 0.26);
}

kbd,
.key {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 1.9rem;
  min-height: 1.75rem;
  padding: 0.18rem 0.55rem;
  border: 1px solid hsl(215 20% 65% / 0.35);
  border-bottom-width: 3px;
  border-radius: 0.55rem;
  background:
    linear-gradient(180deg, hsl(0 0% 100%), hsl(210 40% 96%));
  color: var(--slate-700);
  box-shadow: 0 8px 18px hsl(222 47% 11% / 0.08);
  font-family: var(--font-sans);
  font-size: 0.78em;
  font-weight: 900;
  line-height: 1;
}

.dark kbd,
.dark .key {
  border-color: hsl(0 0% 100% / 0.15);
  background:
    linear-gradient(180deg, hsl(0 0% 100% / 0.12), hsl(0 0% 100% / 0.04));
  color: hsl(210 40% 96%);
  box-shadow: 0 8px 18px hsl(0 0% 0% / 0.25);
}

input,
select,
textarea {
  width: 100%;
  border: 1px solid var(--border);
  border-radius: 1rem;
  background: hsl(0 0% 100% / 0.68);
  color: var(--text);
  box-shadow: 0 10px 30px hsl(222 47% 11% / 0.06);
  transition:
    border-color 220ms var(--ease-out),
    box-shadow 220ms var(--ease-out),
    background-color 220ms var(--ease-out);
  backdrop-filter: blur(18px);
  -webkit-backdrop-filter: blur(18px);
}

.dark input,
.dark select,
.dark textarea {
  background: hsl(0 0% 100% / 0.055);
  color: hsl(210 40% 98%);
}

input::placeholder,
textarea::placeholder {
  color: hsl(215 16% 47% / 0.72);
}

.dark input::placeholder,
.dark textarea::placeholder {
  color: hsl(215 20% 72% / 0.56);
}

input:focus,
select:focus,
textarea:focus {
  border-color: hsl(169 100% 59% / 0.62);
  box-shadow:
    0 0 0 5px hsl(169 100% 59% / 0.12),
    0 16px 44px hsl(188 86% 53% / 0.14);
}

.leaderboard-list,
.score-list,
ol,
ul {
  scrollbar-width: thin;
  scrollbar-color: hsl(188 86% 53% / 0.7) transparent;
}

.leaderboard-item,
.score-row,
.rank-row {
  position: relative;
  border: 1px solid var(--border);
  border-radius: 1.1rem;
  background: hsl(0 0% 100% / 0.52);
  transition:
    transform 220ms var(--ease-out),
    border-color 220ms var(--ease-out),
    background-color 220ms var(--ease-out),
    box-shadow 220ms var(--ease-out);
}

.dark .leaderboard-item,
.dark .score-row,
.dark .rank-row {
  background: hsl(0 0% 100% / 0.045);
}

.leaderboard-item:hover,
.score-row:hover,
.rank-row:hover {
  transform: translateY(-2px);
  border-color: hsl(169 100% 59% / 0.34);
  box-shadow: 0 14px 34px hsl(188 86% 53% / 0.13);
}

.loading,
.is-loading {
  position: relative;
  pointer-events: none;
  color: transparent !important;
}

.loading::after,
.is-loading::after {
  content: "";
  position: absolute;
  left: 50%;
  top: 50%;
  width: 1.15em;
  height: 1.15em;
  margin-left: -0.575em;
  margin-top: -0.575em;
  border: 2px solid currentColor;
  border-color: hsl(216 64% 7% / 0.22);
  border-top-color: hsl(216 64% 7%);
  border-radius: 999px;
  animation: spin 760ms linear infinite;
}

.dark .loading::after,
.dark .is-loading::after {
  border-color: hsl(0 0% 100% / 0.22);
  border-top-color: var(--neon-mint);
}

.animate-fade-in,
[data-animate="fade-in"] {
  animation: fadeIn 560ms var(--ease-out) both;
}

.animate-slide-up,
[data-animate="slide-up"] {
  animation: slideUp 680ms var(--ease-out) both;
}

.animate-scale-in,
[data-animate="scale-in"] {
  animation: scaleIn 520ms var(--ease-elastic) both;
}

.animate-pulse-glow,
[data-animate="pulse-glow"] {
  animation: pulseGlow 2.4s ease-in-out infinite;
}

.snake-segment,
.food-dot,
.power-up {
  filter: drop-shadow(0 0 10px hsl(169 100% 59% / 0.46));
}

.food-dot {
  animation: foodPulse 1.15s ease-in-out infinite;
}

.power-up {
  animation: powerUpFloat 1.6s ease-in-out infinite;
}

#footer,
.site-footer,
footer {
  position: relative;
}

#footer::before,
.site-footer::before,
footer::before {
  content: "";
  position: absolute;
  left: 50%;
  top: 0;
  width: min(72rem, calc(100% - 2rem));
  height: 1px;
  transform: translateX(-50%);
  background: linear-gradient(90deg, transparent, hsl(188 86% 53% / 0.34), hsl(258 90% 66% / 0.3), transparent);
}

@media (hover: hover) and (pointer: fine) {
  .card:hover,
  .game-card:hover,
  .stat-card:hover,
  .settings-card:hover {
    transform: translateY(-4px);
    border-color: hsl(169 100% 59% / 0.24);
    box-shadow:
      var(--shadow-lg),
      0 0 60px hsl(169 100% 59% / 0.08);
  }

  .magnetic:hover {
    transform: translateY(-3px) scale(1.015);
  }
}

@media (max-width: 1024px) {
  #app-shell::before {
    background-size: 34px 34px;
  }

  #game-board-wrapper::before,
  .game-board-wrapper::before,
  .canvas-shell::before,
  #canvas-shell::before,
  .board-shell::before {
    background-size: 20px 20px;
  }
}

@media (max-width: 768px) {
  :root {
    --radius-xl: 1.65rem;
    --radius-lg: 1.35rem;
  }

  body {
    background:
      radial-gradient(circle at 20% 4%, hsl(169 100% 59% / 0.14), transparent 22rem),
      radial-gradient(circle at 88% 18%, hsl(258 90% 66% / 0.12), transparent 24rem),
      var(--bg);
  }

  #site-header {
    backdrop-filter: blur(18px);
    -webkit-backdrop-filter: blur(18px);
  }

  #brand-mark {
    width: 2.5rem;
    height: 2.5rem;
    border-radius: 1rem;
  }

  #brand-name {
    font-size: 1.05rem;
  }

  #brand-tagline {
    font-size: 0.65rem;
    letter-spacing: 0.18em;
  }

  #theme-toggle-button {
    min-width: 2.75rem;
    padding-inline: 0.8rem;
  }

  #hero-section h1,
  .hero-title,
  h1 {
    letter-spacing: -0.055em;
    line-height: 0.98;
  }

  .glass,
  .panel,
  .card,
  .game-card,
  .stat-card,
  .settings-card,
  #game-panel,
  #stats-panel,
  #controls-panel,
  #settings-panel,
  #leaderboard-panel,
  #instructions-panel {
    backdrop-filter: blur(18px) saturate(1.15);
    -webkit-backdrop-filter: blur(18px) saturate(1.15);
  }

  .difficulty-group,
  .segmented-control,
  .tabs {
    width: 100%;
    justify-content: stretch;
    border-radius: 1.25rem;
  }

  .difficulty-button,
  .tab-button,
  .segment-button {
    flex: 1 1 0;
    padding-inline: 0.7rem;
    text-align: center;
  }

  .control-button,
  .direction-button,
  .mobile-control-button,
  [data-direction] {
    min-width: 3.25rem;
    min-height: 3.25rem;
    border-radius: 1.1rem;
  }

  canvas,
  #game-canvas,
  .game-canvas,
  #snake-board,
  .snake-board {
    border-radius: 1.15rem;
  }
}

@media (max-width: 480px) {
  #app-shell::before {
    opacity: 0.36;
    background-size: 28px 28px;
  }

  #main-navigation {
    padding-inline: 1rem;
  }

  #brand-tagline {
    display: none;
  }

  .score-value,
  #score-value,
  #score,
  #high-score,
  #best-score,
  .stat-value {
    letter-spacing: -0.04em;
  }

  .badge,
  .pill,
  .status-pill,
  #game-status,
  #difficulty-badge {
    font-size: 0.78rem;
  }

  .primary-button,
  .secondary-button,
  #start-button,
  #restart-button,
  #play-button,
  #resume-button,
  #pause-button,
  #reset-button {
    width: 100%;
    justify-content: center;
  }

  kbd,
  .key {
    min-width: 1.65rem;
    min-height: 1.55rem;
    padding-inline: 0.42rem;
    border-radius: 0.45rem;
  }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    scroll-behavior: auto !important;
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
  }
}

@keyframes spin {
  to {
    transform: rotate(360deg);
  }
}

@keyframes shimmer {
  0% {
    transform: translateX(-130%);
  }

  100% {
    transform: translateX(130%);
  }
}

@keyframes fadeIn {
  from {
    opacity: 0;
  }

  to {
    opacity: 1;
  }
}

@keyframes slideUp {
  from {
    opacity: 0;
    transform: translateY(18px);
  }

  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes scaleIn {
  from {
    opacity: 0;
    transform: scale(0.94);
  }

  to {
    opacity: 1;
    transform: scale(1);
  }
}

@keyframes pulseDot {
  0%,
  100% {
    opacity: 0.72;
    transform: scale(0.92);
    box-shadow: 0 0 10px hsl(169 100% 59% / 0.45);
  }

  50% {
    opacity: 1;
    transform: scale(1.16);
    box-shadow: 0 0 22px hsl(169 100% 59% / 0.9);
  }
}

@keyframes pulseGlow {
  0%,
  100% {
    box-shadow:
      0 18px 42px hsl(188 86% 53% / 0.2),
      0 0 0 0 hsl(169 100% 59% / 0.18);
  }

  50% {
    box-shadow:
      0 24px 62px hsl(188 86% 53% / 0.3),
      0 0 0 10px hsl(169 100% 59% / 0.02);
  }
}

@keyframes orbFloat {
  0% {
    transform: translate3d(0, 0, 0) scale(1);
  }

  50% {
    transform: translate3d(34px, -24px, 0) scale(1.08);
  }

  100% {
    transform: translate3d(-18px, 26px, 0) scale(0.96);
  }
}

@keyframes foodPulse {
  0%,
  100% {
    transform: scale(1);
    filter: drop-shadow(0 0 8px hsl(43 96% 56% / 0.45));
  }

  50% {
    transform: scale(1.18);
    filter: drop-shadow(0 0 18px hsl(43 96% 56% / 0.88));
  }
}

@keyframes powerUpFloat {
  0%,
  100% {
    transform: translateY(0) rotate(0deg);
    filter: drop-shadow(0 0 12px hsl(258 90% 66% / 0.52));
  }

  50% {
    transform: translateY(-4px) rotate(4deg);
    filter: drop-shadow(0 0 22px hsl(258 90% 66% / 0.9));
  }
}

@keyframes scanline {
  0% {
    transform: translateY(-100%);
    opacity: 0;
  }

  18%,
  82% {
    opacity: 0.28;
  }

  100% {
    transform: translateY(100%);
    opacity: 0;
  }
}

.scanline,
#game-board-wrapper .scanline,
.game-board-wrapper .scanline {
  position: absolute;
  inset-inline: 0;
  top: 0;
  z-index: 3;
  height: 38%;
  pointer-events: none;
  background: linear-gradient(180deg, transparent, hsl(169 100% 59% / 0.18), transparent);
  animation: scanline 4.8s linear infinite;
}

.crt-vignette {
  position: absolute;
  inset: 0;
  z-index: 4;
  pointer-events: none;
  border-radius: inherit;
  background:
    radial-gradient(circle at center, transparent 52%, hsl(216 64% 7% / 0.28) 100%);
  mix-blend-mode: multiply;
}

.dark .crt-vignette {
  mix-blend-mode: normal;
  background:
    radial-gradient(circle at center, transparent 48%, hsl(0 0% 0% / 0.36) 100%);
}