:root {
  --bg: #0f1117;
  --surface: #171a23;
  --surface-2: #1f2330;
  --border: #2a2f3d;
  --text: #e7e9ee;
  --muted: #9aa1b1;
  --accent: #8b7cff;
  --accent-2: #4fd1c5;
  --a: #8b7cff;   /* set A / primary */
  --b: #4fd1c5;   /* set B */
  --result: #ff8a5c; /* operation result */
  --warn: #ffcc66;
  --radius: 14px;
  --shadow: 0 8px 30px rgba(0, 0, 0, 0.35);
  font-synthesis: none;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; scroll-padding-top: 70px; }

body {
  margin: 0;
  background: radial-gradient(1200px 600px at 80% -10%, rgba(139, 124, 255, 0.16), transparent 60%), var(--bg);
  color: var(--text);
  font-family: ui-sans-serif, system-ui, -apple-system, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  line-height: 1.55;
  -webkit-font-smoothing: antialiased;
}

.wrap { max-width: 1080px; margin: 0 auto; padding: 0 20px; }

a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }

/* header */
.site-header { padding: 56px 0 28px; }
.site-header h1 {
  font-size: clamp(2.2rem, 6vw, 3.4rem);
  margin: 0 0 0.2em;
  letter-spacing: -0.02em;
  background: linear-gradient(120deg, var(--accent), var(--accent-2));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}
.tagline { font-size: 1.15rem; color: var(--text); max-width: 60ch; margin: 0 0 0.8em; }
.meta { color: var(--muted); font-size: 0.92rem; }
.meta .dot { margin: 0 0.5em; }
.meta .wip { color: var(--warn); }

/* nav */
.site-nav {
  position: sticky; top: 0; z-index: 10;
  background: rgba(15, 17, 23, 0.85);
  backdrop-filter: blur(10px);
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
}
.site-nav .wrap { display: flex; gap: 8px; flex-wrap: wrap; padding-top: 10px; padding-bottom: 10px; }
.site-nav a {
  padding: 6px 12px; border-radius: 999px; color: var(--muted);
  font-size: 0.9rem; font-weight: 500;
}
.site-nav a:hover { background: var(--surface-2); color: var(--text); text-decoration: none; }

/* cards */
main { padding: 32px 0 64px; display: flex; flex-direction: column; gap: 28px; }
.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  overflow: hidden;
  scroll-margin-top: 70px;
}
.card-head { padding: 22px 24px 6px; }
.card-head h2 { margin: 0 0 0.25em; font-size: 1.35rem; letter-spacing: -0.01em; }
.card-head p { margin: 0; color: var(--muted); max-width: 70ch; }

.card-body {
  display: grid;
  grid-template-columns: minmax(260px, 360px) 1fr;
  gap: 8px 28px;
  padding: 18px 24px 26px;
  align-items: start;
}
@media (max-width: 760px) {
  .card-body { grid-template-columns: 1fr; }
}

/* controls */
.controls { display: flex; flex-direction: column; gap: 14px; }
.field { display: flex; flex-direction: column; gap: 6px; font-size: 0.9rem; color: var(--muted); }
.field > span { font-weight: 500; }
.field strong { color: var(--accent-2); font-variant-numeric: tabular-nums; }

select, input[type="range"] { width: 100%; }
select {
  background: var(--surface-2); color: var(--text);
  border: 1px solid var(--border); border-radius: 8px; padding: 8px 10px;
  font-size: 0.92rem; font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
}
input[type="range"] { accent-color: var(--accent); height: 22px; }

.params { display: flex; flex-direction: column; gap: 10px; }
.param-row { display: grid; grid-template-columns: 1.6em 1fr 3.2em; align-items: center; gap: 8px; }
.param-row label { color: var(--muted); font-family: ui-monospace, SFMono-Regular, Menlo, monospace; font-size: 0.9rem; }
.param-row output { text-align: right; color: var(--accent-2); font-variant-numeric: tabular-nums; font-size: 0.88rem; }

fieldset.set-block {
  border: 1px solid var(--border); border-radius: 10px; padding: 12px 14px 14px; margin: 0;
}
fieldset.set-block legend { padding: 0 6px; color: var(--muted); font-size: 0.82rem; font-weight: 600; text-transform: uppercase; letter-spacing: 0.05em; }

/* readout + code */
.readout { display: grid; grid-template-columns: auto 1fr; gap: 2px 12px; margin: 4px 0 0; font-size: 0.88rem; }
.readout dt { color: var(--muted); }
.readout dd { margin: 0; text-align: right; font-variant-numeric: tabular-nums; color: var(--text); }
.readout dd.bool-true { color: var(--accent-2); }
.readout dd.bool-false { color: var(--result); }

.callout {
  display: block; background: var(--surface-2); border: 1px solid var(--border);
  border-radius: 8px; padding: 9px 11px; font-size: 0.82rem;
  font-family: ui-monospace, SFMono-Regular, Menlo, monospace; color: var(--accent);
  white-space: pre-wrap; word-break: break-word;
}
.status { margin: 0; font-size: 0.85rem; color: var(--warn); min-height: 1.2em; }

/* chart */
.chart-wrap { position: relative; width: 100%; aspect-ratio: 16 / 10; min-height: 260px; }
@media (max-width: 760px) { .chart-wrap { aspect-ratio: 4 / 3; } }

/* footer */
.site-footer { border-top: 1px solid var(--border); padding: 28px 0 48px; color: var(--muted); font-size: 0.9rem; }
.site-footer p { margin: 0 0 0.5em; }
.site-footer .refs { font-size: 0.82rem; }