/* ── Design tokens ─────────────────────────────────────────────── */
: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(1340px, calc(100% - 2rem));
  margin: 0 auto;
  padding: 1.5rem 0 2.5rem;
}

/* ── Hero ───────────────────────────────────────────────────────── */
.hero {
  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(1.9rem, 4vw, 3.2rem);
  line-height: 0.95;
}

.intro {
  max-width: 72ch;
  margin: 0.6rem 0 0;
  color: var(--muted);
  font-size: 1rem;
}

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

/* ── Two-panel canvas row ───────────────────────────────────────── */
.sim-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
  margin-bottom: 1rem;
}

.canvas-panel {
  padding: 0.85rem;
}

.canvas-panel h2 {
  margin: 0 0 0.65rem;
  font-size: 1.05rem;
  color: var(--muted);
  font-weight: 700;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

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

canvas {
  display: block;
  width: 100%;
  height: auto;
}

/* ── Controls panel ─────────────────────────────────────────────── */
.controls-panel {
  padding: 1.25rem 1.5rem;
}

.controls-inner {
  display: grid;
  grid-template-columns: 1fr 1fr 1fr;
  gap: 1.5rem 2rem;
  align-items: start;
}

.control-group {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
}

.control-group label {
  font-weight: 700;
  font-size: 0.97rem;
}

.control-group .sub-label {
  margin: 0;
  color: var(--muted);
  font-size: 0.88rem;
  line-height: 1.35;
}

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

select {
  width: 100%;
  padding: 0.65rem 0.75rem;
  border: 1px solid rgba(21, 48, 77, 0.16);
  border-radius: 14px;
  font: inherit;
  color: var(--ink);
  background: rgba(255, 255, 255, 0.9);
  cursor: pointer;
}

.value-readout {
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--accent-strong);
}

.slider-row { display: flex; align-items: center; gap: 0.4rem; }
.slider-unit { font-size: 0.8rem; color: var(--muted); }
.num-input {
  width: 5rem; padding: 0.3rem 0.4rem;
  border: 1.5px solid rgba(21,48,77,0.14); border-radius: 8px;
  background: white; color: var(--ink);
  font: inherit; font-size: 0.95rem;
  text-align: right; font-variant-numeric: tabular-nums;
}
.num-input:focus { outline: 2px solid var(--accent-strong); outline-offset: 1px; }
.num-input::-webkit-outer-spin-button,
.num-input::-webkit-inner-spin-button { -webkit-appearance: none; margin: 0; }
.num-input { -moz-appearance: textfield; }

/* ── Spectrum panel header ───────────────────────────────────────── */
.panel-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
  margin-bottom: 0.65rem;
}

.panel-header h2 {
  margin: 0;
}

.zoom-group {
  display: flex;
  gap: 0.3rem;
}

.zoom-btn {
  padding: 0.3rem 0.65rem;
  border: 1px solid rgba(21, 48, 77, 0.16);
  border-radius: 999px;
  font: inherit;
  font-size: 0.85rem;
  font-weight: 700;
  color: var(--muted);
  background: rgba(255, 255, 255, 0.9);
  cursor: pointer;
  transition: background 0.15s, color 0.15s;
}

.zoom-btn.active {
  color: white;
  background: linear-gradient(135deg, var(--accent), var(--accent-strong));
  border-color: transparent;
}

/* ── Collapsible schematic ──────────────────────────────────────── */
.schematic-summary {
  padding: 0.85rem 1rem;
  cursor: pointer;
  font-size: 1.05rem;
  color: var(--muted);
  font-weight: 700;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  list-style: none;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  user-select: none;
}

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

.schematic-summary::before {
  content: '▶';
  font-size: 0.65rem;
  color: var(--accent);
  transition: transform 0.2s;
  display: inline-block;
}

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

.schematic-body {
  margin: 0 0.85rem 0.85rem;
}

/* ── Responsive ─────────────────────────────────────────────────── */
@media (max-width: 860px) {
  .sim-row {
    grid-template-columns: 1fr;
  }
  .controls-inner {
    grid-template-columns: 1fr 1fr;
  }
}

@media (max-width: 560px) {
  .controls-inner {
    grid-template-columns: 1fr;
  }
}