: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 ── */

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

.hero-actions {
  display: flex;
  gap: 0.75rem;
  flex-wrap: wrap;
  justify-content: end;
}

.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;
  color: var(--muted);
  font-size: 1rem;
  margin-top: 0.5rem;
}

/* ── Layout ── */

.layout {
  display: grid;
  grid-template-columns: minmax(320px, 390px) 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 ── */

.controls { padding: 1.25rem; }
.controls h2 {
  margin-top: 0;
  margin-bottom: 0.75rem;
  font-size: 1.15rem;
}
.controls h2:not(:first-child) {
  margin-top: 1.25rem;
}

.constants {
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
  padding: 0.85rem 1rem;
  border-radius: 14px;
  background: rgba(239, 247, 255, 0.95);
}

.v-control {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  padding: 0.85rem 1rem;
  border-radius: 14px;
  background: rgba(239, 247, 255, 0.95);
}
.v-control input[type="range"] {
  width: 100%;
  accent-color: var(--accent-strong);
}

.const-row {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 0.75rem;
}

.k-label {
  font-size: 0.9rem;
  color: var(--muted);
}

.k-val {
  font-weight: 700;
  font-size: 0.95rem;
}

.mono { font-family: "Courier New", monospace; }

.num-input {
  width: 5rem;
  padding: 0.2rem 0.35rem;
  border: 1.5px solid rgba(21,48,77,0.14);
  border-radius: 8px;
  background: white;
  color: var(--ink);
  font: inherit;
  font-family: "Courier New", monospace;
  font-size: 0.95rem;
  font-weight: 700;
  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; }

.explainer {
  padding: 0.85rem 1rem;
  background: rgba(239, 247, 255, 0.95);
  border-radius: 14px;
  font-size: 0.92rem;
  line-height: 1.5;
}
.explainer p { margin: 0.45rem 0; }
.explainer p:first-child { margin-top: 0; }
.explainer p:last-child { margin-bottom: 0; }
.muted { color: var(--muted); }

/* ── Toggle buttons ── */

.toggle-button {
  padding: 0.85rem 1.15rem;
  border: 0;
  border-radius: 999px;
  font: inherit;
  font-weight: 700;
  color: white;
  background: linear-gradient(135deg, #475569, #64748b);
  cursor: pointer;
  box-shadow: 0 10px 24px rgba(71, 85, 105, 0.22);
  transition: background 0.15s, transform 0.05s;
}
.toggle-button.active {
  background: linear-gradient(135deg, var(--accent), var(--accent-strong));
  box-shadow: 0 10px 24px rgba(15, 118, 110, 0.28);
}
.toggle-button:active { transform: translateY(1px); }

/* ── Canvas ── */

.visual-panel {
  padding: 0.85rem;
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
}

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

.scope-wrap {
  background: linear-gradient(180deg, #0b1220, #111d33);
}

canvas {
  display: block;
  width: 100%;
  height: auto;
  cursor: default;
  touch-action: manipulation;
}

#sim {
  aspect-ratio: 960 / 540;
  cursor: crosshair;
}
#scope {
  aspect-ratio: 960 / 480;
}

/* ── Responsive ── */

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