:root {
  color-scheme: dark;
  --bg: #071014;
  --panel: rgba(8, 22, 28, 0.78);
  --panel-strong: rgba(10, 30, 38, 0.9);
  --line: #42e8f4;
  --sample: #ffd166;
  --quant: #7cff9b;
  --code: #b48cff;
  --restore: #ff4f64;
  --text: #eefbff;
  --muted: #a9c2c9;
  --grid: rgba(106, 216, 220, 0.12);
  --border: rgba(161, 242, 255, 0.22);
}

* {
  box-sizing: border-box;
}

[hidden] {
  display: none !important;
}

html,
body {
  width: 100%;
  height: 100%;
  margin: 0;
  overflow: hidden;
  background: var(--bg);
  color: var(--text);
  font-family: "Yu Gothic", "Hiragino Kaku Gothic ProN", Meiryo, system-ui, sans-serif;
}

button,
input {
  font: inherit;
}

#stage {
  position: fixed;
  inset: 0;
  width: 100vw;
  height: 100vh;
  display: block;
}

.start-overlay {
  position: fixed;
  inset: 0;
  z-index: 20;
  display: grid;
  place-items: center;
  padding: 28px;
  background:
    radial-gradient(circle at 28% 24%, rgba(66, 232, 244, 0.2), transparent 34%),
    radial-gradient(circle at 76% 64%, rgba(180, 140, 255, 0.18), transparent 32%),
    rgba(3, 7, 10, 0.86);
  transition: opacity 480ms ease, visibility 480ms ease;
}

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

.start-panel {
  width: min(720px, 92vw);
  padding: 34px;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: linear-gradient(160deg, rgba(10, 28, 34, 0.92), rgba(14, 12, 28, 0.9));
  box-shadow: 0 0 46px rgba(66, 232, 244, 0.22), inset 0 0 30px rgba(255, 255, 255, 0.04);
  text-align: center;
}

.start-kicker {
  color: var(--sample);
  font-weight: 800;
  letter-spacing: 0;
  margin-bottom: 12px;
}

.start-panel h1 {
  margin: 0;
  font-size: clamp(32px, 5vw, 58px);
  line-height: 1.18;
}

.start-panel p {
  margin: 18px auto 0;
  max-width: 58ch;
  font-size: clamp(17px, 2.2vw, 22px);
  color: var(--muted);
  line-height: 1.7;
}

.start-button {
  margin-top: 28px;
  width: min(460px, 100%);
  padding: 18px 24px;
  border: 1px solid rgba(255, 255, 255, 0.28);
  border-radius: 8px;
  color: #041015;
  background: linear-gradient(90deg, #42e8f4, #7cff9b 52%, #ffd166);
  box-shadow: 0 0 24px rgba(66, 232, 244, 0.42);
  cursor: pointer;
  transition: transform 160ms ease, filter 160ms ease;
}

.start-button:hover,
.start-button:focus-visible {
  transform: translateY(-2px);
  filter: brightness(1.08);
  outline: none;
}

.start-button span,
.start-button strong {
  display: block;
}

.start-button span {
  font-size: clamp(18px, 2.6vw, 24px);
  font-weight: 800;
}

.start-button strong {
  margin-top: 4px;
  font-size: clamp(13px, 1.7vw, 16px);
}

.start-note {
  font-size: 15px !important;
}

.hud {
  position: fixed;
  z-index: 5;
  top: 18px;
  left: 24px;
  right: 24px;
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 18px;
  pointer-events: none;
}

.hud-label {
  color: var(--muted);
  font-size: clamp(13px, 1.5vw, 16px);
  font-weight: 700;
}

.hud-title {
  margin-top: 3px;
  font-size: clamp(24px, 3.4vw, 42px);
  line-height: 1.16;
  font-weight: 900;
  text-shadow: 0 0 18px rgba(66, 232, 244, 0.38);
}

.hud-badges {
  display: flex;
  flex-wrap: wrap;
  justify-content: flex-end;
  gap: 8px;
}

.badge {
  display: inline-flex;
  align-items: center;
  min-height: 34px;
  padding: 6px 10px;
  border: 1px solid var(--border);
  border-radius: 8px;
  color: var(--text);
  background: var(--panel);
  font-size: clamp(12px, 1.45vw, 15px);
  font-weight: 800;
  backdrop-filter: blur(12px);
}

.badge-source {
  color: var(--sample);
}

.message-panel {
  position: fixed;
  z-index: 6;
  left: 24px;
  bottom: 98px;
  width: min(760px, calc(100vw - 48px));
  padding: 18px 20px 16px;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--panel);
  box-shadow: 0 0 24px rgba(66, 232, 244, 0.16);
  backdrop-filter: blur(12px);
  pointer-events: none;
}

.message-panel h2 {
  margin: 0 0 6px;
  font-size: clamp(22px, 3vw, 36px);
  line-height: 1.18;
}

.message-panel p {
  margin: 0;
  color: var(--muted);
  font-size: clamp(16px, 2vw, 22px);
  line-height: 1.5;
}

.next-hint {
  margin-top: 10px;
  color: #071014;
  background: linear-gradient(90deg, var(--sample), #ffe9a8);
  border-radius: 8px;
  padding: 7px 12px;
  display: inline-flex;
  font-size: clamp(14px, 1.8vw, 18px);
  font-weight: 900;
}

.param-panel {
  position: fixed;
  z-index: 7;
  left: 24px;
  right: 24px;
  bottom: 92px;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 14px;
  padding: 10px 14px;
  border: 1px solid rgba(124, 255, 155, 0.32);
  border-radius: 8px;
  background: rgba(6, 18, 20, 0.86);
  box-shadow: 0 0 24px rgba(124, 255, 155, 0.15);
  backdrop-filter: blur(14px);
}

.param-panel h2 {
  display: none;
}

.control-row {
  display: grid;
  grid-template-columns: max-content minmax(160px, 24vw) 5.2em 2.5em;
  align-items: center;
  gap: 8px;
  margin: 0;
  color: var(--text);
  font-size: clamp(14px, 1.6vw, 17px);
  font-weight: 800;
}

.control-row input[type="range"] {
  accent-color: var(--quant);
  min-width: 0;
}

.control-row input[type="number"] {
  width: 100%;
  padding: 7px 8px;
  border: 1px solid var(--border);
  border-radius: 6px;
  color: var(--text);
  background: rgba(0, 0, 0, 0.36);
}

.unit {
  color: var(--muted);
}

.param-stats {
  display: none;
}

.notice {
  position: fixed;
  z-index: 8;
  right: 24px;
  bottom: 98px;
  max-width: min(520px, calc(100vw - 48px));
  padding: 12px 14px;
  border: 1px solid rgba(255, 209, 102, 0.44);
  border-radius: 8px;
  color: #fff4c2;
  background: rgba(38, 27, 6, 0.9);
  box-shadow: 0 0 18px rgba(255, 209, 102, 0.2);
  font-weight: 800;
}

.step-splash {
  position: fixed;
  z-index: 9;
  inset: 0;
  display: grid;
  place-items: center;
  color: var(--text);
  font-size: clamp(42px, 9vw, 116px);
  font-weight: 1000;
  text-align: center;
  text-shadow: 0 0 28px rgba(66, 232, 244, 0.72), 0 0 58px rgba(180, 140, 255, 0.34);
  pointer-events: none;
}

.step-splash.is-visible {
  animation: splash-pop 880ms ease forwards;
}

@keyframes splash-pop {
  0% {
    opacity: 0;
    transform: scale(0.72);
  }
  18% {
    opacity: 1;
    transform: scale(1.06);
  }
  72% {
    opacity: 0.92;
    transform: scale(1);
  }
  100% {
    opacity: 0;
    transform: scale(0.96);
  }
}

.space-flash {
  position: fixed;
  z-index: 4;
  inset: 8px;
  border: 2px solid rgba(66, 232, 244, 0);
  border-radius: 8px;
  pointer-events: none;
}

.space-flash.is-active {
  animation: flash-frame 420ms ease-out;
}

@keyframes flash-frame {
  0% {
    border-color: rgba(66, 232, 244, 0.95);
    box-shadow: inset 0 0 18px rgba(66, 232, 244, 0.54), 0 0 24px rgba(66, 232, 244, 0.4);
  }
  100% {
    border-color: rgba(66, 232, 244, 0);
    box-shadow: none;
  }
}

.legend {
  position: fixed;
  z-index: 6;
  left: 0;
  right: 0;
  bottom: 0;
  min-height: 78px;
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 1px;
  padding: 10px 18px 14px;
  background: linear-gradient(180deg, rgba(3, 9, 12, 0.68), rgba(3, 9, 12, 0.96));
  border-top: 1px solid var(--border);
  backdrop-filter: blur(14px);
}

.legend-item {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  min-width: 0;
  padding: 8px 10px;
  color: var(--muted);
  font-size: clamp(13px, 1.7vw, 20px);
  font-weight: 900;
  border-radius: 8px;
  transition: color 220ms ease, background 220ms ease, transform 220ms ease;
}

.legend-item.is-active {
  color: var(--text);
  background: rgba(255, 255, 255, 0.08);
  transform: translateY(-2px);
}

.legend-item.is-complete::after {
  content: "✓";
  display: inline-grid;
  place-items: center;
  width: 22px;
  height: 22px;
  border-radius: 50%;
  color: #041015;
  background: var(--quant);
  font-size: 14px;
  font-weight: 1000;
}

.legend-icon {
  position: relative;
  width: 44px;
  height: 28px;
  flex: 0 0 auto;
}

.icon-wave::before {
  content: "";
  position: absolute;
  left: 1px;
  right: 1px;
  top: 13px;
  height: 3px;
  background: var(--line);
  box-shadow: 0 0 12px var(--line);
  transform: skewY(-12deg);
}

.icon-sampling::before,
.icon-sampling::after {
  content: "";
  position: absolute;
  background: var(--sample);
  box-shadow: 0 0 12px var(--sample);
}

.icon-sampling::before {
  left: 7px;
  top: 2px;
  width: 3px;
  height: 24px;
}

.icon-sampling::after {
  left: 24px;
  top: 9px;
  width: 12px;
  height: 12px;
  border-radius: 50%;
}

.icon-quantizing::before {
  content: "";
  position: absolute;
  left: 4px;
  right: 4px;
  top: 6px;
  height: 17px;
  border-top: 3px solid var(--quant);
  border-bottom: 3px solid var(--quant);
  box-shadow: 0 0 12px var(--quant);
}

.icon-encoding::before {
  content: "01";
  position: absolute;
  inset: 0;
  color: var(--code);
  font-family: Consolas, "Courier New", monospace;
  font-size: 24px;
  line-height: 28px;
  font-weight: 1000;
  text-shadow: 0 0 12px var(--code);
}

.legend-item.is-active .legend-icon {
  animation: legend-pulse 900ms ease-in-out infinite alternate;
}

@keyframes legend-pulse {
  from {
    filter: drop-shadow(0 0 4px currentColor);
    transform: scale(1);
  }
  to {
    filter: drop-shadow(0 0 16px currentColor);
    transform: scale(1.12);
  }
}

@media (max-width: 760px) {
  .hud {
    left: 14px;
    right: 14px;
    top: 12px;
    flex-direction: column;
  }

  .hud-badges {
    justify-content: flex-start;
  }

  .message-panel,
  .notice {
    left: 14px;
    right: 14px;
    width: auto;
    bottom: 86px;
  }

  .notice {
    top: auto;
    bottom: clamp(218px, 34vh, 300px);
  }

  .param-panel {
    left: 14px;
    right: 14px;
    bottom: 94px;
    flex-wrap: wrap;
    justify-content: stretch;
  }

  .control-row {
    width: 100%;
    grid-template-columns: 7.5em minmax(110px, 1fr) 4.8em 2.5em;
  }

  .control-row span:first-child {
    grid-column: auto;
  }

  .legend {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    min-height: 86px;
    padding: 8px 8px 10px;
  }

  .legend-icon {
    width: 34px;
  }
}

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