:root {
  --bg: #0b1020;
  --bg-soft: rgba(14, 23, 45, 0.76);
  --card: rgba(20, 30, 56, 0.88);
  --card-border: rgba(255, 255, 255, 0.08);
  --text: #f4f7ff;
  --muted: #a9b7d6;
  --accent: #7c9cff;
  --accent-2: #53d1b6;
  --shadow: 0 24px 60px rgba(0, 0, 0, 0.35);
  --u: #f4f6fb;
  --r: #ff5f5f;
  --f: #39d98a;
  --d: #ffd447;
  --l: #ff8f3f;
  --b: #4d7dff;
}

* {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  min-height: 100%;
  background:
    radial-gradient(circle at top, rgba(124, 156, 255, 0.24), transparent 35%),
    radial-gradient(circle at bottom, rgba(83, 209, 182, 0.16), transparent 40%),
    var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "SF Pro Display", "PingFang SC", "Helvetica Neue", sans-serif;
  overscroll-behavior: none;
}

body {
  padding: 18px 14px 28px;
}

button {
  font: inherit;
}

.app-shell {
  width: min(100%, 980px);
  margin: 0 auto;
}

.hero-card,
.panel {
  background: var(--card);
  backdrop-filter: blur(20px);
  border: 1px solid var(--card-border);
  box-shadow: var(--shadow);
}

.hero-card {
  border-radius: 28px;
  padding: 20px;
  display: grid;
  gap: 20px;
}

.eyebrow {
  margin: 0 0 8px;
  color: var(--accent-2);
  font-size: 12px;
  letter-spacing: 0.24em;
}

h1,
h2,
h3,
p {
  margin: 0;
}

h1 {
  font-size: clamp(30px, 7vw, 42px);
  line-height: 1;
  margin-bottom: 10px;
}

.hero-desc,
.panel-head p,
.hero-tip,
.helper-card li,
.scramble-box p {
  color: var(--muted);
  line-height: 1.55;
}

.stats-row {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 12px;
  margin-top: 18px;
}

.stat-pill {
  padding: 14px 14px 12px;
  border-radius: 18px;
  background: rgba(255, 255, 255, 0.06);
  border: 1px solid rgba(255, 255, 255, 0.05);
}

.stat-pill-wide {
  grid-column: span 2;
}

.stat-label {
  display: block;
  color: var(--muted);
  font-size: 12px;
  margin-bottom: 8px;
}

.stat-pill strong {
  font-size: 22px;
}

.hero-visual {
  padding: 18px;
  border-radius: 24px;
  background: linear-gradient(180deg, rgba(124, 156, 255, 0.12), rgba(255, 255, 255, 0.04));
  border: 1px solid rgba(255, 255, 255, 0.06);
}

.cube-viewport {
  height: 210px;
  display: grid;
  place-items: center;
  perspective: 900px;
}

.hero-cube {
  position: relative;
  width: 130px;
  height: 130px;
  transform-style: preserve-3d;
  transform: rotateX(-26deg) rotateY(-38deg);
  transition: transform 0.12s ease-out;
}

.hero-face {
  position: absolute;
  inset: 0;
  border-radius: 18px;
  border: 3px solid rgba(255, 255, 255, 0.14);
  box-shadow: inset 0 0 0 2px rgba(255, 255, 255, 0.05), 0 20px 35px rgba(0, 0, 0, 0.2);
  background-image:
    linear-gradient(rgba(255, 255, 255, 0.16), rgba(255, 255, 255, 0.02)),
    linear-gradient(90deg, rgba(0, 0, 0, 0.12) 33%, transparent 33%, transparent 66%, rgba(0, 0, 0, 0.12) 66%),
    linear-gradient(rgba(0, 0, 0, 0.12) 33%, transparent 33%, transparent 66%, rgba(0, 0, 0, 0.12) 66%);
  background-size: 100% 100%, 43px 100%, 100% 43px;
}

.hero-face-front {
  transform: translateZ(65px);
  background-color: var(--f);
}

.hero-face-right {
  transform: rotateY(90deg) translateZ(65px);
  background-color: var(--r);
}

.hero-face-top {
  transform: rotateX(90deg) translateZ(65px);
  background-color: var(--u);
}

.hero-tip {
  margin-top: 12px;
  font-size: 13px;
  text-align: center;
}

.main-grid {
  display: grid;
  gap: 16px;
  margin-top: 16px;
}

.panel {
  border-radius: 24px;
  padding: 18px;
}

.panel-head {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 16px;
}

.panel-head.compact {
  margin-bottom: 14px;
}

.ghost-button,
.action-button,
.move-button {
  border: 0;
  cursor: pointer;
  transition: transform 0.12s ease, opacity 0.12s ease, box-shadow 0.12s ease;
}

.ghost-button:active,
.action-button:active,
.move-button:active {
  transform: scale(0.97);
}

.ghost-button {
  padding: 11px 14px;
  border-radius: 14px;
  background: rgba(255, 255, 255, 0.08);
  color: var(--text);
}

.cube-net-wrap {
  overflow-x: auto;
  padding-bottom: 6px;
}

.cube-net {
  min-width: 310px;
  display: grid;
  grid-template-columns: repeat(12, 24px);
  grid-template-rows: repeat(9, 24px);
  gap: 4px;
  justify-content: center;
}

.face-card {
  display: grid;
  grid-template-columns: repeat(3, 24px);
  grid-template-rows: repeat(3, 24px);
  gap: 4px;
  padding: 6px;
  border-radius: 14px;
  background: rgba(255, 255, 255, 0.05);
  box-shadow: inset 0 0 0 1px rgba(255, 255, 255, 0.03);
}

.face-label {
  position: absolute;
  top: -18px;
  left: 2px;
  color: var(--muted);
  font-size: 11px;
}

.face-slot {
  position: relative;
}

.sticker {
  width: 24px;
  height: 24px;
  border-radius: 7px;
  box-shadow:
    inset 0 2px 4px rgba(255, 255, 255, 0.24),
    inset 0 -2px 4px rgba(0, 0, 0, 0.14),
    0 3px 8px rgba(0, 0, 0, 0.2);
  border: 1px solid rgba(255, 255, 255, 0.12);
}

.legend {
  display: flex;
  flex-wrap: wrap;
  gap: 10px 14px;
  margin-top: 14px;
  color: var(--muted);
  font-size: 13px;
}

.legend.hidden {
  display: none;
}

.legend span {
  display: inline-flex;
  align-items: center;
  gap: 8px;
}

.legend-swatch {
  width: 14px;
  height: 14px;
  border-radius: 4px;
  display: inline-block;
}

.swatch-u { background: var(--u); }
.swatch-r { background: var(--r); }
.swatch-f { background: var(--f); }
.swatch-d { background: var(--d); }
.swatch-l { background: var(--l); }
.swatch-b { background: var(--b); }

.scramble-box,
.helper-card {
  margin-top: 16px;
  padding: 14px;
  border-radius: 18px;
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid rgba(255, 255, 255, 0.05);
}

.scramble-label {
  display: block;
  margin-bottom: 8px;
  color: var(--accent-2);
  font-size: 12px;
  letter-spacing: 0.12em;
}

.primary-actions {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 10px;
}

.action-button {
  min-height: 52px;
  padding: 0 12px;
  border-radius: 16px;
  background: rgba(255, 255, 255, 0.08);
  color: var(--text);
  box-shadow: 0 12px 22px rgba(0, 0, 0, 0.18);
}

.action-button.accent {
  background: linear-gradient(135deg, var(--accent), #8d6dff);
}

.move-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 10px;
  margin-top: 14px;
}

.move-button {
  min-height: 62px;
  padding: 10px 8px;
  border-radius: 18px;
  color: var(--text);
  background: linear-gradient(180deg, rgba(255, 255, 255, 0.1), rgba(255, 255, 255, 0.04));
  box-shadow: 0 14px 22px rgba(0, 0, 0, 0.16);
}

.move-button strong {
  display: block;
  font-size: 21px;
  margin-bottom: 6px;
}

.move-button span {
  display: block;
  font-size: 12px;
  color: var(--muted);
}

.helper-card h3 {
  margin-bottom: 10px;
}

.helper-card ol {
  padding-left: 18px;
  margin: 0;
}

.helper-card li + li {
  margin-top: 8px;
}

.toast {
  position: fixed;
  left: 50%;
  bottom: 28px;
  transform: translateX(-50%) translateY(20px);
  min-width: 180px;
  max-width: calc(100vw - 32px);
  padding: 12px 16px;
  border-radius: 16px;
  text-align: center;
  background: rgba(5, 10, 24, 0.92);
  color: var(--text);
  border: 1px solid rgba(255, 255, 255, 0.08);
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.2s ease, transform 0.2s ease;
  z-index: 50;
}

.toast.show {
  opacity: 1;
  transform: translateX(-50%) translateY(0);
}

.pulse {
  animation: pulse 0.35s ease;
}

@keyframes pulse {
  0% { transform: scale(0.98); }
  50% { transform: scale(1.02); }
  100% { transform: scale(1); }
}

@media (min-width: 820px) {
  body {
    padding: 24px;
  }

  .hero-card {
    grid-template-columns: 1.2fr 0.9fr;
    align-items: center;
    padding: 24px;
  }

  .main-grid {
    grid-template-columns: 1.25fr 0.95fr;
    align-items: start;
  }
}