:root {
  color-scheme: dark;
  --bg: #07111f;
  --panel: rgba(8, 15, 30, 0.72);
  --panel-strong: rgba(11, 20, 40, 0.92);
  --line: rgba(255, 255, 255, 0.1);
  --text: #eff4ff;
  --muted: rgba(239, 244, 255, 0.72);
  --accent: #4dd0ff;
  --accent-2: #7c5cff;
  --shadow: 0 28px 80px rgba(0, 0, 0, 0.35);
  --cubie: 3.4rem;
  --gap: 0.14rem;
  --half: calc(var(--cubie) / 2);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

* {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  min-height: 100%;
  background:
    radial-gradient(circle at top left, rgba(124, 92, 255, 0.24), transparent 34%),
    radial-gradient(circle at top right, rgba(77, 208, 255, 0.18), transparent 28%),
    linear-gradient(180deg, #040814, var(--bg));
  color: var(--text);
}

body {
  overflow-x: hidden;
}

.bg-orb {
  position: fixed;
  inset: auto;
  border-radius: 50%;
  filter: blur(42px);
  opacity: 0.55;
  pointer-events: none;
}

.orb-a {
  width: 22rem;
  height: 22rem;
  left: -7rem;
  top: 3rem;
  background: rgba(77, 208, 255, 0.17);
}

.orb-b {
  width: 28rem;
  height: 28rem;
  right: -10rem;
  bottom: -8rem;
  background: rgba(124, 92, 255, 0.15);
}

.app-shell {
  width: min(1200px, calc(100vw - 2rem));
  margin: 0 auto;
  padding: 2rem 0 3rem;
}

.hero {
  display: flex;
  justify-content: space-between;
  gap: 1.5rem;
  align-items: end;
  margin-bottom: 1.5rem;
}

.eyebrow {
  margin: 0 0 0.5rem;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  font-size: 0.78rem;
  color: var(--accent);
}

h1 {
  margin: 0;
  font-size: clamp(2.4rem, 6vw, 4.8rem);
  line-height: 0.95;
}

.subtitle {
  max-width: 42rem;
  margin: 0.8rem 0 0;
  color: var(--muted);
  font-size: 1rem;
  line-height: 1.7;
}

.score-card {
  min-width: 14rem;
  padding: 1rem 1.1rem;
  border: 1px solid var(--line);
  border-radius: 1.2rem;
  background: linear-gradient(180deg, rgba(255, 255, 255, 0.08), rgba(255, 255, 255, 0.03));
  box-shadow: var(--shadow);
  backdrop-filter: blur(14px);
}

.score-label,
.move-count {
  display: block;
  color: var(--muted);
  font-size: 0.88rem;
}

.score-card strong {
  display: block;
  margin: 0.55rem 0 0.25rem;
  font-size: 1.35rem;
}

.workspace {
  display: grid;
  grid-template-columns: minmax(0, 1.2fr) minmax(310px, 0.8fr);
  gap: 1.2rem;
  align-items: start;
}

.stage,
.panel {
  border: 1px solid var(--line);
  border-radius: 1.5rem;
  background: var(--panel);
  box-shadow: var(--shadow);
  backdrop-filter: blur(16px);
}

.stage {
  padding: 1.2rem;
}

.stage-frame {
  min-height: 34rem;
  display: grid;
  place-items: center;
  border-radius: 1.1rem;
  background:
    radial-gradient(circle at center, rgba(255, 255, 255, 0.07), transparent 52%),
    linear-gradient(180deg, rgba(255, 255, 255, 0.03), rgba(0, 0, 0, 0.12));
  overflow: hidden;
  position: relative;
}

.cube-scene {
  width: min(30rem, 100%);
  height: min(30rem, 100%);
  perspective: 1500px;
  display: grid;
  place-items: center;
  touch-action: none;
  position: relative;
}

.cube-scene::before {
  content: "";
  position: absolute;
  width: 18rem;
  height: 18rem;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(0, 0, 0, 0.55), transparent 68%);
  filter: blur(18px);
  transform: translateY(9rem) scale(1.1);
  opacity: 0.8;
}

.cube {
  position: relative;
  width: var(--cubie);
  height: var(--cubie);
  transform-style: preserve-3d;
  transform: rotateX(-30deg) rotateY(38deg);
  transition: transform 80ms linear;
}

.cubie {
  position: absolute;
  inset: 0;
  transform-style: preserve-3d;
  transition: transform 220ms ease;
  will-change: transform;
}

.cubie::after {
  content: "";
  position: absolute;
  inset: 0.12rem;
  border-radius: 0.4rem;
  background: rgba(0, 0, 0, 0.14);
  transform: translateZ(-0.12rem);
}

.sticker {
  position: absolute;
  inset: calc(var(--gap) * 1.3);
  border-radius: 0.45rem;
  box-shadow:
    inset 0 0 0 1px rgba(0, 0, 0, 0.45),
    0 0.22rem 0.7rem rgba(0, 0, 0, 0.2);
  backface-visibility: hidden;
}

.face {
  position: absolute;
  inset: 0;
  transform-style: preserve-3d;
  background: linear-gradient(180deg, rgba(255, 255, 255, 0.06), rgba(0, 0, 0, 0.18));
  border-radius: 0.5rem;
}

.face.u { transform: rotateX(90deg) translateZ(var(--half)); }
.face.d { transform: rotateX(-90deg) translateZ(var(--half)); }
.face.r { transform: rotateY(90deg) translateZ(var(--half)); }
.face.l { transform: rotateY(-90deg) translateZ(var(--half)); }
.face.f { transform: translateZ(var(--half)); }
.face.b { transform: rotateY(180deg) translateZ(var(--half)); }

.face.hidden {
  opacity: 0;
}

.face.u,
.face.d,
.face.l,
.face.r,
.face.f,
.face.b {
  box-shadow: inset 0 0 0 1px rgba(255, 255, 255, 0.04);
}

.panel {
  padding: 1.15rem;
}

.panel-block + .panel-block {
  margin-top: 1.2rem;
}

.panel h2 {
  margin: 0 0 0.8rem;
  font-size: 1rem;
}

.action-grid,
.move-grid {
  display: grid;
  gap: 0.75rem;
}

.view-grid {
  display: grid;
  gap: 0.8rem;
}

.view-field {
  display: grid;
  gap: 0.45rem;
  color: var(--muted);
  font-size: 0.9rem;
}

.view-input-row {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 5rem;
  gap: 0.6rem;
  align-items: center;
}

.view-input-row input[type="range"] {
  width: 100%;
}

.view-input-row input[type="number"] {
  width: 100%;
  appearance: none;
  border: 1px solid rgba(255, 255, 255, 0.12);
  border-radius: 0.75rem;
  background: rgba(255, 255, 255, 0.06);
  color: var(--text);
  padding: 0.7rem 0.75rem;
  font: inherit;
}

.view-actions {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0.75rem;
}

.action-grid {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.move-grid {
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

button {
  appearance: none;
  border: 1px solid rgba(255, 255, 255, 0.12);
  border-radius: 0.9rem;
  background: rgba(255, 255, 255, 0.06);
  color: var(--text);
  padding: 0.8rem 0.9rem;
  font: inherit;
  cursor: pointer;
  transition: transform 160ms ease, background 160ms ease, border-color 160ms ease;
}

button:hover {
  transform: translateY(-1px);
  border-color: rgba(77, 208, 255, 0.38);
  background: rgba(255, 255, 255, 0.1);
}

button:active {
  transform: translateY(0);
}

button.primary {
  background: linear-gradient(135deg, rgba(77, 208, 255, 0.26), rgba(124, 92, 255, 0.22));
  border-color: rgba(77, 208, 255, 0.28);
}

.move-btn {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 0.75rem;
}

.move-btn code {
  padding: 0.15rem 0.38rem;
  border-radius: 0.4rem;
  background: rgba(0, 0, 0, 0.25);
  color: #fff;
}

.notes {
  margin: 0;
  padding-left: 1.1rem;
  color: var(--muted);
  line-height: 1.7;
}

.tutorial {
  border: 1px solid rgba(255, 255, 255, 0.1);
  border-radius: 1rem;
  background: rgba(255, 255, 255, 0.04);
  overflow: hidden;
}

.tutorial + .tutorial {
  margin-top: 0.75rem;
}

.tutorial summary {
  list-style: none;
  cursor: pointer;
  padding: 0.95rem 1rem;
  color: var(--text);
  font-weight: 600;
  border-bottom: 1px solid rgba(255, 255, 255, 0.06);
}

.tutorial summary::-webkit-details-marker {
  display: none;
}

.tutorial-body {
  padding: 0.95rem 1rem 1rem;
  color: var(--muted);
  line-height: 1.7;
}

.tutorial-body p {
  margin: 0 0 0.8rem;
}

.tutorial-steps,
.tutorial-list {
  margin: 0;
  padding-left: 1.1rem;
}

.tutorial-steps li + li,
.tutorial-list li + li {
  margin-top: 0.65rem;
}

.tutorial-steps strong,
.tutorial-list strong {
  color: var(--text);
}

.tutorial-steps span {
  display: block;
  margin-top: 0.2rem;
}

.tutorial-tip {
  margin-top: 0.9rem;
  padding: 0.85rem 0.9rem;
  border-left: 3px solid var(--accent);
  border-radius: 0.6rem;
  background: rgba(77, 208, 255, 0.08);
  color: var(--text);
}

.hint {
  margin: 0.9rem 0 0;
  text-align: center;
  color: var(--muted);
}

.back-home {
  margin: 1rem 0 0;
  text-align: center;
}

.back-home a {
  display: inline-block;
  padding: 0.55rem 0.95rem;
  border-radius: 999px;
  border: 1px solid rgba(255, 255, 255, 0.2);
  background: rgba(255, 255, 255, 0.08);
  color: var(--text);
  text-decoration: none;
  transition: transform 160ms ease, border-color 160ms ease, background 160ms ease;
}

.back-home a:hover,
.back-home a:focus-visible {
  transform: translateY(-1px);
  border-color: rgba(77, 208, 255, 0.38);
  background: rgba(255, 255, 255, 0.13);
  outline: none;
}

kbd {
  display: inline-block;
  min-width: 1.8rem;
  padding: 0.18rem 0.42rem;
  border-radius: 0.45rem;
  border: 1px solid rgba(255, 255, 255, 0.16);
  background: rgba(255, 255, 255, 0.07);
  color: var(--text);
  font: inherit;
  font-size: 0.88rem;
}

@media (max-width: 980px) {
  .hero,
  .workspace {
    grid-template-columns: 1fr;
    display: grid;
  }

  .score-card {
    min-width: 0;
  }

  .stage-frame {
    min-height: 28rem;
  }
}

@media (max-width: 640px) {
  .app-shell {
    width: min(100vw - 1rem, 1200px);
    padding-top: 1rem;
  }

  .stage {
    padding: 0.85rem;
  }

  .cube-scene {
    width: 100%;
    height: 22rem;
  }

  .cube {
    transform: rotateX(-26deg) rotateY(36deg);
  }

  .action-grid,
  .move-grid {
    grid-template-columns: 1fr 1fr;
  }

  .move-grid {
    grid-template-columns: 1fr;
  }
}