/* ---------- 3D Shape Explorer — kid-friendly textbook look ---------- */
:root {
  --ink: #1f2430;
  --ink-soft: #5a6272;
  --accent: #4f46e5;
  --accent-soft: #eef2ff;
  --card: #ffffff;
  --bg: #f4f6fb;
  --radius: 18px;
  --shadow: 0 1px 3px rgba(31, 36, 48, .08), 0 8px 24px rgba(31, 36, 48, .07);
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  font-family: "Segoe UI", system-ui, -apple-system, "Helvetica Neue", Arial, sans-serif;
  color: var(--ink);
  background:
    radial-gradient(1200px 500px at 85% -10%, #ffe9f0 0%, transparent 60%),
    radial-gradient(1000px 500px at -10% 0%, #e7ecff 0%, transparent 55%),
    var(--bg);
  min-height: 100dvh;
}

.app-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 14px 20px 6px;
  max-width: 1280px;
  margin: 0 auto;
}
.app-header h1 {
  margin: 0;
  font-size: clamp(1.25rem, 3.4vw, 1.7rem);
  letter-spacing: .2px;
  background: linear-gradient(90deg, #4f46e5, #db2777);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}
.tagline { margin: 2px 0 0; color: var(--ink-soft); font-size: .9rem; }

.install-btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  border: 0;
  border-radius: 999px;
  padding: 10px 16px;
  font-size: .95rem;
  font-weight: 700;
  color: #fff;
  background: var(--accent);
  box-shadow: var(--shadow);
  cursor: pointer;
}
.install-btn svg { width: 18px; height: 18px; }

/* ---------- layout ---------- */
.layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 400px;
  gap: 16px;
  max-width: 1280px;
  margin: 0 auto;
  padding: 10px 20px 28px;
  align-items: start;
}
@media (max-width: 960px) {
  .layout { grid-template-columns: 1fr; padding: 8px 12px 24px; }
}

/* ---------- stage (graph-paper canvas) ---------- */
#stage-wrap {
  position: relative;
  border-radius: var(--radius);
  background:
    linear-gradient(rgba(99, 130, 255, .07) 1px, transparent 1px) 0 0 / 24px 24px,
    linear-gradient(90deg, rgba(99, 130, 255, .07) 1px, transparent 1px) 0 0 / 24px 24px,
    linear-gradient(rgba(99, 130, 255, .12) 1.5px, transparent 1.5px) 0 0 / 120px 120px,
    linear-gradient(90deg, rgba(99, 130, 255, .12) 1.5px, transparent 1.5px) 0 0 / 120px 120px,
    #ffffff;
  box-shadow: var(--shadow);
  overflow: hidden;
  touch-action: none; /* we handle pointer gestures ourselves */
  height: min(72dvh, 720px);
  min-height: 380px;
}
@media (max-width: 960px) {
  #stage-wrap { height: 52dvh; min-height: 320px; }
}
#scene {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  display: block;
  cursor: grab;
}
#scene:active { cursor: grabbing; }

#stage-hint {
  position: absolute;
  left: 50%;
  bottom: 10px;
  transform: translateX(-50%);
  font-size: .8rem;
  color: var(--ink-soft);
  background: rgba(255, 255, 255, .85);
  border: 1px solid rgba(31, 36, 48, .08);
  border-radius: 999px;
  padding: 5px 14px;
  pointer-events: none;
  white-space: nowrap;
  backdrop-filter: blur(4px);
}

/* ---------- panel cards ---------- */
#panel {
  display: flex;
  flex-direction: column;
  gap: 14px;
}
@media (max-width: 960px) {
  #panel {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    align-items: start;
  }
  #shape-card { grid-column: 1 / -1; }
}

.card {
  background: var(--card);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 16px 18px;
}
.card h2 {
  margin: 0 0 12px;
  font-size: .82rem;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: .12em;
  color: var(--ink-soft);
}

/* ---------- shape buttons ---------- */
.shape-grid {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 8px;
}
@media (max-width: 380px) { .shape-grid { grid-template-columns: repeat(3, 1fr); } }
.shape-btn {
  appearance: none;
  border: 2px solid transparent;
  background: var(--accent-soft);
  color: var(--accent);
  border-radius: 14px;
  padding: 10px 4px 8px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 6px;
  font-size: .8rem;
  font-weight: 700;
  cursor: pointer;
  transition: transform .12s ease, box-shadow .12s ease, background .12s ease;
  min-height: 74px;
}
.shape-btn svg { width: 34px; height: 34px; }
.shape-btn:hover { transform: translateY(-2px); box-shadow: var(--shadow); }
.shape-btn.active {
  background: var(--accent);
  color: #fff;
  border-color: var(--accent);
  box-shadow: 0 6px 16px rgba(79, 70, 229, .35);
}

/* ---------- sliders ---------- */
.slider-row {
  display: grid;
  grid-template-columns: 92px 1fr 64px;
  align-items: center;
  gap: 10px;
  padding: 7px 0;
}
.slider-row.hidden { display: none; }
.slider-label { font-size: .9rem; font-weight: 600; color: var(--ink); }
.slider-row output {
  font-size: .85rem;
  font-weight: 700;
  color: var(--accent);
  text-align: right;
  font-variant-numeric: tabular-nums;
}
input[type="range"] {
  width: 100%;
  accent-color: var(--accent);
  height: 28px;
  cursor: pointer;
}

/* ---------- colors ---------- */
.color-row {
  display: grid;
  grid-template-columns: 92px 1fr;
  gap: 4px 10px;
  align-items: center;
  padding: 6px 0;
}
.color-row .slider-label { grid-row: span 2; }
.swatches { display: flex; flex-wrap: wrap; gap: 6px; }
.swatch {
  width: 26px;
  height: 26px;
  border-radius: 50%;
  border: 2px solid rgba(31, 36, 48, .12);
  cursor: pointer;
  padding: 0;
  transition: transform .1s ease, box-shadow .1s ease;
}
.swatch:hover { transform: scale(1.15); }
.swatch.selected {
  border-color: var(--ink);
  box-shadow: 0 0 0 2px #fff inset;
}
.color-row input[type="color"] {
  grid-column: 2;
  justify-self: end;
  width: 52px;
  height: 30px;
  border: 1px solid rgba(31, 36, 48, .15);
  border-radius: 8px;
  background: #fff;
  padding: 2px;
  cursor: pointer;
}

/* ---------- toggles ---------- */
.toggle-row {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 8px 0;
  font-size: .95rem;
  font-weight: 600;
  cursor: pointer;
}
.toggle-row input {
  width: 20px;
  height: 20px;
  accent-color: var(--accent);
  cursor: pointer;
}

/* ---------- facts ---------- */
.legend { display: flex; flex-wrap: wrap; gap: 8px; margin-bottom: 10px; }
.legend .chip {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  font-size: .82rem;
  font-weight: 600;
  background: var(--accent-soft);
  border-radius: 999px;
  padding: 5px 12px 5px 7px;
}
.legend .dot {
  width: 16px;
  height: 16px;
  border-radius: 5px;
  border: 1.5px solid rgba(31, 36, 48, .2);
}

.stats { display: flex; gap: 8px; flex-wrap: wrap; margin-bottom: 10px; }
.stat {
  flex: 1 1 auto;
  min-width: 86px;
  text-align: center;
  background: linear-gradient(180deg, #ffffff, #f5f7ff);
  border: 1.5px solid #e3e8ff;
  border-radius: 12px;
  padding: 8px 6px;
}
.stat .num { font-size: 1.35rem; font-weight: 800; color: var(--accent); }
.stat .lbl {
  font-size: .7rem;
  text-transform: uppercase;
  letter-spacing: .08em;
  color: var(--ink-soft);
  font-weight: 700;
}

.facts-desc {
  margin: 0;
  font-size: .92rem;
  line-height: 1.5;
  color: var(--ink);
}

/* safe-area for notched phones in standalone mode */
@media (display-mode: standalone) {
  .app-header { padding-top: calc(14px + env(safe-area-inset-top)); }
  .layout { padding-bottom: calc(28px + env(safe-area-inset-bottom)); }
}