:root {
  --bg: #2f2f2f;
  --logo-width: min(34vw, 280px);
  --logo-ratio: 676.61 / 535.58;
  --rx: 0;
  --ry: 0;
  --arrow-color: #fff8ec;
  --arrow-shadow: rgba(255, 248, 236, 0.22);
  --toggle-shell: rgba(255, 255, 255, 0.08);
  --toggle-border: rgba(255, 255, 255, 0.18);
  --toggle-text: rgba(255, 248, 236, 0.7);
  --toggle-active: #fff8ec;
  --toggle-thumb:
    linear-gradient(135deg, #fff8ec 0%, #feb944 38%, #df5584 68%, #5a5ca8 100%);
  --toggle-glow: rgba(254, 185, 68, 0.28);
  --layer-1-filter: brightness(0) saturate(100%) invert(96%) sepia(16%) saturate(483%) hue-rotate(315deg) brightness(107%) contrast(106%);
  --layer-2-filter:
    brightness(0) saturate(100%) invert(82%) sepia(46%) saturate(2168%) hue-rotate(329deg) brightness(103%) contrast(99%)
    drop-shadow(0 0 2px #feb944)
    drop-shadow(0 0 10px #feb944);
  --layer-3-filter:
    brightness(0) saturate(100%) invert(66%) sepia(75%) saturate(3560%) hue-rotate(329deg) brightness(101%) contrast(99%)
    drop-shadow(0 0 2px #fe6842)
    drop-shadow(0 0 10px #fe6842);
  --layer-4-filter:
    brightness(0) saturate(100%) invert(53%) sepia(35%) saturate(1475%) hue-rotate(295deg) brightness(95%) contrast(84%)
    drop-shadow(0 0 2px #df5584)
    drop-shadow(0 0 10px #df5584);
  --layer-5-filter:
    brightness(0) saturate(100%) invert(39%) sepia(19%) saturate(1335%) hue-rotate(199deg) brightness(97%) contrast(89%)
    drop-shadow(0 0 2px #5a5ca8)
    drop-shadow(0 0 10px #5a5ca8);
}

body[data-theme="dark"] {
  --bg: #0b0b0d;
  --logo-ratio: 490 / 394.09;
  --arrow-color: #e7f7ea;
  --arrow-shadow: rgba(112, 255, 163, 0.14);
  --toggle-shell: rgba(255, 255, 255, 0.06);
  --toggle-border: rgba(112, 255, 163, 0.18);
  --toggle-text: rgba(231, 247, 234, 0.68);
  --toggle-active: #ffffff;
  --toggle-thumb:
    linear-gradient(135deg, #050505 0%, #0f3b22 22%, #1d8f52 52%, #74ffb2 100%);
  --toggle-glow: rgba(116, 255, 178, 0.22);
  --layer-1-filter:
    brightness(0) saturate(100%) invert(0%) sepia(4%) saturate(544%) hue-rotate(246deg) brightness(95%) contrast(102%);
  --layer-2-filter:
    brightness(0) saturate(100%) invert(17%) sepia(66%) saturate(1107%) hue-rotate(119deg) brightness(92%) contrast(95%)
    drop-shadow(0 0 2px #0f6b38)
    drop-shadow(0 0 10px rgba(15, 107, 56, 0.32));
  --layer-3-filter:
    brightness(0) saturate(100%) invert(42%) sepia(59%) saturate(1040%) hue-rotate(111deg) brightness(94%) contrast(91%)
    drop-shadow(0 0 2px #23995a)
    drop-shadow(0 0 10px rgba(35, 153, 90, 0.28));
  --layer-4-filter:
    brightness(0) saturate(100%) invert(69%) sepia(41%) saturate(734%) hue-rotate(102deg) brightness(98%) contrast(96%)
    drop-shadow(0 0 2px #57d48b)
    drop-shadow(0 0 10px rgba(87, 212, 139, 0.24));
  --layer-5-filter:
    brightness(0) saturate(100%) invert(88%) sepia(16%) saturate(764%) hue-rotate(85deg) brightness(101%) contrast(97%)
    drop-shadow(0 0 2px #b8ffd4)
    drop-shadow(0 0 10px rgba(184, 255, 212, 0.2));
}

* {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  min-height: 100%;
}

body {
  background: var(--bg);
  overflow: hidden;
  transition: background 220ms ease;
}

.back-link {
  position: fixed;
  top: 1.25rem;
  left: 1.5rem;
  z-index: 20;
  color: var(--arrow-color);
  text-decoration: none;
  font-size: clamp(2.5rem, 6vw, 4.5rem);
  line-height: 1;
  font-family: "IBM Plex Sans", "Avenir Next", "Segoe UI", sans-serif;
  text-shadow: 0 0 10px var(--arrow-shadow);
  transition: transform 160ms ease, opacity 160ms ease;
}

.back-link:hover {
  transform: translateX(-6px);
  opacity: 0.9;
}

.theme-toggle {
  position: fixed;
  left: 50%;
  bottom: 1.75rem;
  z-index: 24;
  isolation: isolate;
  display: grid;
  grid-template-columns: 1fr 1fr;
  align-items: center;
  gap: 0;
  width: min(320px, calc(100vw - 2.5rem));
  padding: 0.36rem;
  border: 1px solid var(--toggle-border);
  border-radius: 999px;
  background: var(--toggle-shell);
  color: var(--toggle-text);
  font: 500 0.82rem/1 "IBM Plex Sans", "Avenir Next", "Segoe UI", sans-serif;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  cursor: pointer;
  backdrop-filter: blur(10px);
  transform: translateX(-50%);
  overflow: hidden;
  box-shadow:
    0 18px 40px rgba(0, 0, 0, 0.18),
    inset 0 1px 0 rgba(255, 255, 255, 0.06);
  transition: transform 160ms ease, background 160ms ease, border-color 160ms ease, color 160ms ease, box-shadow 160ms ease;
}

.theme-toggle:hover {
  transform: translateX(-50%) translateY(-2px);
}

.theme-toggle-track {
  position: absolute;
  inset: 0.34rem;
  border-radius: 999px;
  pointer-events: none;
}

.theme-toggle-thumb {
  position: absolute;
  top: 0;
  left: 0;
  width: calc(50% - 0.12rem);
  height: 100%;
  border-radius: 999px;
  background: var(--toggle-thumb);
  box-shadow:
    0 0 0 1px rgba(255, 255, 255, 0.08) inset,
    0 0 22px var(--toggle-glow);
  transition: transform 240ms cubic-bezier(0.2, 0.9, 0.2, 1), box-shadow 240ms ease, background 240ms ease;
}

body[data-theme="dark"] .theme-toggle-thumb {
  transform: translateX(calc(100% + 0.24rem));
}

.theme-toggle-burst {
  position: absolute;
  top: 50%;
  width: 52px;
  height: 52px;
  border-radius: 50%;
  opacity: 0;
  filter: blur(8px);
  transform: translateY(-50%) scale(0.7);
  transition: opacity 220ms ease, transform 260ms ease;
}

.burst-left {
  left: 16%;
  background: radial-gradient(circle, rgba(254, 185, 68, 0.4), transparent 70%);
}

.burst-right {
  right: 16%;
  background: radial-gradient(circle, rgba(116, 255, 178, 0.4), transparent 70%);
}

.theme-toggle:hover .burst-left,
.theme-toggle:hover .burst-right,
.theme-toggle:focus-visible .burst-left,
.theme-toggle:focus-visible .burst-right {
  opacity: 1;
  transform: translateY(-50%) scale(1);
}

.theme-toggle-option {
  position: relative;
  z-index: 1;
  display: grid;
  place-items: center;
  min-height: 3.35rem;
  transition: color 180ms ease, opacity 180ms ease;
}

.toggle-icon {
  display: inline-block;
  font-size: 1.15rem;
  line-height: 1;
  transition: transform 220ms ease, filter 220ms ease;
}

.icon-sun {
  transform: rotate(0deg) scale(1);
  filter: drop-shadow(0 0 8px rgba(255, 248, 236, 0.28));
}

.icon-orb {
  transform: rotate(-10deg) scale(1);
  filter: drop-shadow(0 0 8px rgba(116, 255, 178, 0.22));
}

body[data-theme="light"] .option-light,
body[data-theme="dark"] .option-dark {
  color: var(--toggle-active);
}

body[data-theme="light"] .option-dark,
body[data-theme="dark"] .option-light {
  opacity: 0.72;
}

body[data-theme="light"] .option-light .icon-sun,
body[data-theme="dark"] .option-dark .icon-orb {
  transform: rotate(12deg) scale(1.08);
}

body[data-theme="dark"] .layer-1 {
  --x-factor: -1.35;
  --y-factor: -0.85;
  --rotate-factor: -0.12;
}

body[data-theme="dark"] .layer-2 {
  --x-factor: 1.05;
  --y-factor: 1.6;
  --rotate-factor: 0.18;
}

body[data-theme="dark"] .layer-3 {
  --x-factor: -1.35;
  --y-factor: -2.1;
  --rotate-factor: -0.24;
}

body[data-theme="dark"] .layer-4 {
  --x-factor: 1.55;
  --y-factor: 2.75;
  --rotate-factor: 0.3;
}

body[data-theme="dark"] .layer-5 {
  --x-factor: -1.8;
  --y-factor: -3.35;
  --rotate-factor: -0.36;
}

.theme-toggle:focus-visible {
  outline: 2px solid var(--toggle-active);
  outline-offset: 3px;
}

.stage {
  display: grid;
  place-items: center;
  min-height: 100vh;
  width: 100%;
}

.mobile-hint {
  position: fixed;
  inset: auto 50% 6.75rem auto;
  z-index: 23;
  display: none;
  width: min(280px, calc(100vw - 2rem));
  padding: 0.9rem 1rem;
  border: 1px solid var(--toggle-border);
  border-radius: 18px;
  background: color-mix(in srgb, var(--bg) 82%, white 18%);
  color: var(--toggle-active);
  text-align: center;
  backdrop-filter: blur(10px);
  transform: translateX(50%);
  box-shadow: 0 16px 36px rgba(0, 0, 0, 0.22);
  opacity: 0;
  transition: opacity 320ms ease, transform 320ms ease;
}

.mobile-hint.is-visible {
  opacity: 1;
  transform: translateX(50%) translateY(-8px);
}

.mobile-hint.is-hidden {
  opacity: 0;
  transform: translateX(50%) translateY(0);
}

.mobile-hint-icon {
  display: grid;
  place-items: center;
  width: 3rem;
  height: 3rem;
  margin: 0 auto 0.45rem;
  border-radius: 50%;
  background: var(--toggle-thumb);
  box-shadow: 0 0 18px var(--toggle-glow);
}

.hand-emoji {
  display: inline-block;
  font-size: 1.35rem;
  line-height: 1;
  color: #fff;
  animation: hand-swipe 1.2s ease-in-out infinite;
}

.mobile-hint-text {
  margin: 0;
  font: 500 0.82rem/1.4 "IBM Plex Sans", "Avenir Next", "Segoe UI", sans-serif;
  letter-spacing: 0.04em;
}

@keyframes hand-swipe {
  0%,
  100% {
    transform: translateX(-6px) rotate(-8deg);
  }

  50% {
    transform: translateX(6px) rotate(8deg);
  }
}

.stack {
  position: relative;
  width: var(--logo-width);
  height: calc(var(--logo-width) * var(--logo-ratio));
}

.logo-layer {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  display: block;
  object-fit: contain;
  transform-origin: center;
  transition: transform var(--duration) ease;
  transform:
    translate3d(
      calc(var(--rx) * var(--x-factor) * 1px),
      calc(var(--ry) * var(--y-factor) * 1px),
      0
    )
    rotate(calc(var(--rx) * var(--rotate-factor) * 1deg))
    scale(var(--scale));
  filter: var(--filter);
  opacity: 0.92;
}

.layer-1 {
  --scale: 1;
  --duration: 50ms;
  --x-factor: -1;
  --y-factor: -0.55;
  --rotate-factor: -0.09;
  --filter: var(--layer-1-filter);
  z-index: 5;
  opacity: 0.98;
}

.layer-2 {
  --scale: 0.95;
  --duration: 100ms;
  --x-factor: 0.75;
  --y-factor: 1.1;
  --rotate-factor: 0.12;
  --filter: var(--layer-2-filter);
  z-index: 4;
}

.layer-3 {
  --scale: 0.9;
  --duration: 150ms;
  --x-factor: -0.95;
  --y-factor: -1.6;
  --rotate-factor: -0.16;
  --filter: var(--layer-3-filter);
  z-index: 3;
}

.layer-4 {
  --scale: 0.85;
  --duration: 200ms;
  --x-factor: 1.15;
  --y-factor: 2.05;
  --rotate-factor: 0.2;
  --filter: var(--layer-4-filter);
  z-index: 2;
}

.layer-5 {
  --scale: 0.8;
  --duration: 250ms;
  --x-factor: -1.35;
  --y-factor: -2.5;
  --rotate-factor: -0.24;
  --filter: var(--layer-5-filter);
  z-index: 1;
}

@media (max-width: 900px) {
  :root {
    --logo-width: min(48vw, 280px);
  }
}

@media (max-width: 640px) {
  :root {
    --logo-width: min(64vw, 260px);
  }

  .back-link {
    top: 1rem;
    left: 1rem;
  }

  .theme-toggle {
    bottom: 1rem;
  }

  .mobile-hint {
    display: block;
  }
}