:root {
  --ink: #2b2b38;
  --muted: #6b6b7a;
  --green: #2fbf7f;
  --blue: #4f8cff;
  --violet: #7b6bff;
}

* { box-sizing: border-box; }

body.viz-page {
  margin: 0;
  min-height: 100vh;
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  color: var(--ink);
  background: linear-gradient(160deg, #0b1026 0%, #16204a 100%);
  padding: 16px 20px;
}

.back {
  position: relative;
  display: inline-block;
  margin-bottom: 12px;
  text-decoration: none;
  color: #eef1ff;
  font-weight: 600;
  padding: 8px 14px;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.1);
  box-shadow: 0 4px 14px rgba(0, 0, 0, 0.25);
  transition: transform 0.15s ease, background 0.15s ease;
}

.back:hover { transform: translateY(-2px); background: rgba(255, 255, 255, 0.18); }

.viz-wrap { max-width: 1200px; margin: 0 auto; }

.viz-header { text-align: center; margin-bottom: 12px; }

.viz-header h1 {
  margin: 0;
  color: #eef1ff;
  font-size: clamp(1.6rem, 3.5vw, 2.2rem);
  letter-spacing: -0.02em;
}

.viz-header .hint {
  margin: 8px auto 0;
  max-width: 720px;
  color: #aab3d6;
  line-height: 1.5;
}

/* ---- Tabs ---- */
.tabs {
  display: flex;
  gap: 8px;
  justify-content: center;
  margin-bottom: 12px;
}

.tab {
  font: inherit;
  font-weight: 700;
  cursor: pointer;
  padding: 10px 20px;
  border: none;
  border-radius: 999px;
  color: #cdd5f2;
  background: rgba(255, 255, 255, 0.08);
  transition: transform 0.12s ease, background 0.12s ease, color 0.12s ease;
}

.tab:hover { transform: translateY(-2px); background: rgba(255, 255, 255, 0.16); }

.tab.active {
  color: #0b1026;
  background: #eef1ff;
}

.canvas-card {
  position: relative;
  background: #06091c;
  border-radius: 18px;
  padding: 12px;
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.4);
}

.canvas-card canvas {
  display: block;
  width: auto;
  max-width: 100%;
  max-height: 62vh;
  margin: 0 auto;
  touch-action: none;
}

.controls {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 14px;
  margin: 14px 0 0;
  background: rgba(255, 255, 255, 0.07);
  padding: 12px 16px;
  border-radius: 16px;
  box-shadow: 0 6px 18px rgba(0, 0, 0, 0.25);
}

.slider-group { display: flex; flex-direction: column; gap: 6px; }

.slider-group label { font-weight: 600; font-size: 0.92rem; color: #cdd5f2; }

.slider-row { display: flex; align-items: center; gap: 12px; }

.slider-row input[type="range"] { width: 200px; accent-color: var(--blue); }

.slider-row output {
  min-width: 46px;
  text-align: center;
  font-weight: 700;
  color: #eef1ff;
  background: rgba(255, 255, 255, 0.12);
  border-radius: 8px;
  padding: 3px 6px;
}

.buttons { display: flex; flex-wrap: wrap; gap: 10px; }

.btn {
  font: inherit;
  cursor: pointer;
  border: none;
  padding: 12px 18px;
  border-radius: 12px;
  font-weight: 700;
  color: #fff;
  transition: transform 0.12s ease, filter 0.12s ease;
}

.btn:hover { transform: translateY(-2px); filter: brightness(1.08); }
.btn:active { transform: translateY(0); }

.btn-go { background: var(--green); }
.btn-reset { background: var(--blue); }
.btn-shuffle { background: var(--violet); }

.toggle-row { margin: 0; }
.toggle {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  cursor: pointer;
  color: #cdd5f2;
  font-weight: 600;
  font-size: 0.92rem;
}

.toggle input { width: 18px; height: 18px; accent-color: var(--blue); }

.status {
  position: absolute;
  top: 12px;
  left: 0;
  right: 0;
  z-index: 2;
  text-align: center;
  font-weight: 700;
  font-size: 1.1rem;
  padding: 0 16px;
  color: #aab3d6;
  line-height: 1.4;
  pointer-events: none;
  text-shadow: 0 2px 8px rgba(0, 0, 0, 0.8);
}

.status.good { color: var(--green); }
.status.bad { color: #ff8f8f; }
.status.help { color: #ffd166; }

.explain {
  margin-top: 14px;
  background: rgba(255, 255, 255, 0.06);
  border-radius: 16px;
  box-shadow: 0 6px 18px rgba(0, 0, 0, 0.2);
}

.explain summary {
  cursor: pointer;
  padding: 16px 20px;
  font-size: 1.05rem;
  font-weight: 700;
  color: #eef1ff;
  list-style: none;
  display: flex;
  align-items: center;
  gap: 10px;
}

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

.explain summary::before {
  content: "▸";
  transition: transform 0.15s ease;
  color: var(--blue);
}

.explain[open] summary::before { transform: rotate(90deg); }

.explain .body { padding: 0 20px 18px; }

.explain p { line-height: 1.6; color: #aab3d6; margin: 0 0 12px; }
.explain p:last-child { margin-bottom: 0; }
.explain strong { color: #eef1ff; }

@media (max-width: 640px) {
  body.viz-page { padding: 12px; }
  .controls { flex-direction: column; align-items: stretch; }
  .buttons { justify-content: center; }
}