:root {
  --bg-top: #eef6ff;
  --bg-bottom: #d7e8ff;
  --panel: rgba(255, 255, 255, 0.82);
  --panel-border: rgba(18, 57, 99, 0.12);
  --ink: #15304d;
  --muted: #55708d;
  --accent: #0f766e;
  --accent-strong: #0d9488;
  --shadow: 0 24px 60px rgba(19, 48, 77, 0.14);
}

* { box-sizing: border-box; }

body {
  margin: 0;
  min-height: 100vh;
  font-family: "Trebuchet MS", "Gill Sans", "Segoe UI", sans-serif;
  color: var(--ink);
  background:
    radial-gradient(circle at top left, rgba(255,255,255,0.85), transparent 30%),
    linear-gradient(180deg, var(--bg-top), var(--bg-bottom));
}

.page {
  width: min(1280px, calc(100% - 2rem));
  margin: 0 auto;
  padding: 1.5rem 0 2rem;
}

.hero {
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  gap: 1rem;
  margin-bottom: 1rem;
}

.hero-link {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  margin-bottom: 0.75rem;
  padding: 0.45rem 0.8rem;
  border-radius: 999px;
  text-decoration: none;
  font-size: 0.9rem;
  font-weight: 700;
  color: var(--ink);
  background: rgba(255,255,255,0.9);
  border: 1px solid rgba(21,48,77,0.12);
}
.hero-link:hover { background: white; }

.eyebrow {
  margin: 0 0 0.35rem;
  color: var(--accent);
  font-size: 0.9rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

h1 {
  margin: 0;
  font-size: clamp(2rem, 5vw, 3.5rem);
  line-height: 0.95;
}

.intro {
  max-width: 68ch;
  margin: 0.6rem 0 0;
  color: var(--muted);
  font-size: 1rem;
}

.muted { color: var(--muted); font-weight: 400; font-style: italic; }

.layout {
  display: grid;
  grid-template-columns: minmax(280px, 340px) minmax(0, 1fr);
  gap: 1rem;
}

.panel {
  background: var(--panel);
  border: 1px solid var(--panel-border);
  border-radius: 24px;
  box-shadow: var(--shadow);
  backdrop-filter: blur(16px);
}

.controls {
  padding: 1.1rem;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.control-group > label {
  display: block;
  margin-bottom: 0.35rem;
  font-weight: 700;
  font-size: 0.92rem;
}

.seg-control {
  display: grid;
  background: rgba(21,48,77,0.07);
  border-radius: 14px;
  padding: 3px;
  gap: 0;
}
.seg-control.cols-3 { grid-template-columns: 1fr 1fr 1fr; }

.seg-btn {
  padding: 0.45rem 0.3rem;
  border: 0;
  border-radius: 11px;
  font: inherit;
  font-size: 0.82rem;
  font-weight: 700;
  color: var(--muted);
  background: transparent;
  cursor: pointer;
  text-align: center;
  line-height: 1.25;
  transition: background 0.15s, color 0.15s;
}
.seg-btn.active {
  background: white;
  color: var(--ink);
  box-shadow: 0 2px 8px rgba(21,48,77,0.12);
}

input[type="range"] {
  width: 100%;
  accent-color: var(--accent-strong);
}

.slider-row {
  display: flex;
  align-items: center;
  gap: 0.4rem;
}

.slider-val {
  font-size: 0.85rem;
  font-weight: 700;
  color: var(--ink);
  min-width: 2.8rem;
  text-align: right;
}

input[type="number"].slider-val {
  width: 4rem;
  min-width: 4rem;
  padding: 0.2rem 0.35rem;
  border: 1.5px solid rgba(21,48,77,0.2);
  border-radius: 7px;
  background: rgba(255,255,255,0.8);
  font: inherit;
  font-size: 0.85rem;
  font-weight: 700;
  color: var(--ink);
  text-align: right;
  font-variant-numeric: tabular-nums;
  -moz-appearance: textfield;
}
input[type="number"].slider-val::-webkit-outer-spin-button,
input[type="number"].slider-val::-webkit-inner-spin-button {
  -webkit-appearance: none;
  margin: 0;
}
input[type="number"].slider-val:focus {
  outline: 2px solid var(--accent-strong);
  outline-offset: 1px;
  background: white;
}

.slider-unit {
  font-size: 0.8rem;
  color: var(--muted);
}

.auto-row {
  display: flex;
  gap: 0.5rem;
}

.play-btn {
  flex: 1;
  padding: 0.5rem 0.6rem;
  border: 1.5px solid rgba(21,48,77,0.14);
  border-radius: 10px;
  font: inherit;
  font-size: 0.86rem;
  font-weight: 700;
  color: var(--ink);
  background: rgba(255,255,255,0.92);
  cursor: pointer;
  transition: background 0.15s, color 0.15s;
}
.play-btn:hover { background: white; }
.play-btn.playing { background: var(--accent-strong); color: white; border-color: var(--accent-strong); }

.explain-card {
  padding: 0.75rem 0.9rem;
  border-radius: 14px;
  background: rgba(239,247,255,0.9);
  border-left: 3px solid var(--accent-strong);
  font-size: 0.88rem;
  line-height: 1.5;
  color: #334155;
}

.readout-hd {
  font-weight: 700;
  color: var(--ink);
  margin-bottom: 0.3rem;
}

.readout-row {
  display: flex;
  justify-content: space-between;
  gap: 0.5rem;
  padding: 0.1rem 0;
}
.readout-row > span:last-child {
  font-weight: 700;
  color: var(--ink);
  font-variant-numeric: tabular-nums;
  text-align: right;
}

.ideal-note {
  margin: 0;
  padding: 0.7rem 0.85rem;
  border-radius: 12px;
  background: rgba(255,247,224,0.85);
  border: 1px solid rgba(180,140,40,0.25);
  font-size: 0.82rem;
  line-height: 1.45;
  color: #5a4416;
}
.ideal-note strong { color: #3d2e08; }

.visual-panel { padding: 0.85rem; }

.canvas-wrap {
  position: relative;
  overflow: hidden;
  border-radius: 18px;
  background: linear-gradient(180deg, rgba(255,255,255,0.82), rgba(225,238,255,0.94));
  aspect-ratio: 12 / 8;
}

#schematic {
  display: block;
  width: 100%;
  height: 100%;
}

.scene-note {
  position: absolute;
  left: 14px;
  bottom: 12px;
  padding: 0.35rem 0.65rem;
  background: rgba(255,255,255,0.85);
  border: 1px solid rgba(21,48,77,0.12);
  border-radius: 10px;
  font-size: 0.75rem;
  color: var(--muted);
  font-weight: 600;
  pointer-events: none;
  max-width: calc(100% - 28px);
}

@media (max-width: 960px) {
  .hero { align-items: flex-start; flex-direction: column; }
  .layout { grid-template-columns: 1fr; }
}