/* Light mode only, matching edwar281.github.io/public. */
:root {
  --paper: #f6f7f9; --surface: #ffffff; --ink: #16202b; --ink-soft: #4a5867; --rule: #d9dee5;
  --accent: #1f5f8b; --accent-ink: #164a6d; --accent-soft: #e3edf5; --code-bg: #f1f4f7;
  --error: #a33a2c; --error-soft: #fbeceb; --ok: #2e7d4f;
  --f-display: "Newsreader", Georgia, serif;
  --f-body: "IBM Plex Sans", system-ui, -apple-system, "Segoe UI", sans-serif;
  --f-mono: "IBM Plex Mono", ui-monospace, Menlo, monospace;
  color-scheme: light;
}
* { box-sizing: border-box; }
body { margin: 0; background: var(--paper); color: var(--ink); font: 400 16px/1.6 var(--f-body); }
a { color: var(--accent); text-underline-offset: 3px; }
p { margin: 0; }
.container { max-width: 960px; margin: 0 auto; padding-inline: 24px; }
.sr-only { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); }
button:focus-visible, a:focus-visible, input:focus-visible, summary:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }

.site-head { border-bottom: 1px solid var(--rule); background: var(--paper); }
.site-head .container { display: flex; justify-content: space-between; align-items: center; min-height: 60px; }
.brand { font: 500 1.2rem/1 var(--f-display); color: var(--ink); text-decoration: none; }
.back { font-size: 0.92rem; font-weight: 500; text-decoration: none; }

main { padding-block: 48px 72px; }
.eyebrow { font: 500 0.75rem/1.2 var(--f-mono); text-transform: uppercase; letter-spacing: 0.14em; color: var(--ink-soft); margin-bottom: 12px; }
h1 { font: 500 clamp(2rem, 5vw, 3rem)/1.1 var(--f-display); margin: 0 0 16px; letter-spacing: -0.015em; }
.lead { font: 400 clamp(1.15rem, 2.2vw, 1.4rem)/1.45 var(--f-display); max-width: 46ch; margin-bottom: 12px; }
.muted { color: var(--ink-soft); }
.small { font-size: 0.88rem; margin-top: 10px; }
.intro { margin-bottom: 32px; }

.chips { display: flex; flex-wrap: wrap; gap: 8px; margin-bottom: 14px; }
.chip { font: 500 0.9rem/1.2 var(--f-body); background: var(--surface); color: var(--ink); border: 1px solid var(--rule);
  border-radius: 999px; padding: 9px 14px; cursor: pointer; text-align: left; }
.chip:hover { border-color: var(--accent); color: var(--accent); }
.chip[aria-pressed="true"] { background: var(--accent-soft); border-color: var(--accent); color: var(--accent-ink); }
.chip:disabled { opacity: .55; cursor: default; }
.ask-form { display: flex; gap: 8px; }
.ask-form input { flex: 1; min-width: 0; font: 400 1rem/1.4 var(--f-body); padding: 11px 14px; border: 1px solid var(--rule);
  border-radius: 6px; background: var(--surface); color: var(--ink); }
.btn { font: 500 0.95rem/1 var(--f-body); background: var(--accent); color: #fff; border: 0; border-radius: 6px; padding: 0 18px; cursor: pointer; }
.btn:hover { background: var(--accent-ink); }
.btn:disabled { opacity: .5; cursor: default; }
.btn.ghost { background: transparent; color: var(--accent); border: 1px solid var(--accent); padding: 8px 12px; }
.status { font-size: 0.86rem; color: var(--ink-soft); margin-top: 10px; min-height: 1.3em; }
.status.warn { color: var(--error); }

.run { margin-top: 40px; display: grid; grid-template-columns: minmax(0, 1fr); gap: 18px; }
.run > *, .step > *, .output > * { min-width: 0; max-width: 100%; }
.run:empty { display: none; }
.question { font: 500 1.45rem/1.3 var(--f-display); padding-bottom: 12px; border-bottom: 1px solid var(--rule); }
.note { color: var(--ink-soft); font-style: italic; }
.step { background: var(--surface); border: 1px solid var(--rule); border-radius: 8px; padding: 16px 18px; display: grid; gap: 10px; min-width: 0; }
.step header { display: flex; gap: 10px; align-items: baseline; }
.badge { font: 500 0.7rem/1 var(--f-mono); text-transform: uppercase; letter-spacing: 0.08em; padding: 4px 7px; border-radius: 4px;
  background: var(--accent-soft); color: var(--accent-ink); flex: none; }
.badge.python { background: #f3eadf; color: #8a4b12; }
.purpose { font-weight: 500; }
.code summary { cursor: pointer; font-size: 0.85rem; color: var(--accent); width: max-content; }
.code pre { margin: 8px 0 0; background: var(--code-bg); border-radius: 6px; padding: 12px; overflow-x: auto; max-height: 340px;
  font: 400 0.82rem/1.5 var(--f-mono); white-space: pre; }
.output { display: grid; gap: 10px; min-width: 0; }
.pending { color: var(--ink-soft); font-size: 0.9rem; }
.stdout { margin: 0; background: var(--code-bg); border-radius: 6px; padding: 10px 12px; font: 400 0.8rem/1.5 var(--f-mono);
  white-space: pre-wrap; max-height: 220px; overflow: auto; }
.error { background: var(--error-soft); color: var(--error); border-radius: 6px; padding: 10px 12px; font: 400 0.8rem/1.5 var(--f-mono); white-space: pre-wrap; }
.error-note { font-size: 0.85rem; color: var(--ink-soft); }
.chart { max-width: 100%; height: auto; border: 1px solid var(--rule); border-radius: 6px; background: #fff; }
.table-wrap { overflow: auto; max-height: 320px; border: 1px solid var(--rule); border-radius: 6px; }
table { border-collapse: collapse; width: 100%; font-size: 0.84rem; font-variant-numeric: tabular-nums; }
th, td { padding: 6px 10px; text-align: left; border-bottom: 1px solid var(--rule); white-space: nowrap; }
th { position: sticky; top: 0; background: #f8fafb; font-weight: 600; }
td.num { text-align: right; }
.table-meta { font-size: 0.78rem; color: var(--ink-soft); }

.answer { background: var(--surface); border: 1px solid var(--accent); border-left-width: 4px; border-radius: 8px; padding: 20px 22px; display: grid; gap: 10px; }
.answer h2 { font: 500 0.75rem/1 var(--f-mono); text-transform: uppercase; letter-spacing: 0.14em; color: var(--accent); margin: 0; }
.answer .body { display: grid; gap: 10px; font-size: 1.02rem; }
.answer ul { margin: 0; padding-left: 20px; display: grid; gap: 4px; }
.trace { display: flex; flex-wrap: wrap; gap: 6px 16px; font: 400 0.78rem/1.4 var(--f-mono); color: var(--ink-soft); }
.trace .live-btn { margin-left: auto; }
.problem { background: var(--error-soft); color: var(--error); border-radius: 8px; padding: 14px 16px; }

.how { margin-top: 72px; }
.section-title { font: 500 0.78rem/1 var(--f-mono); text-transform: uppercase; letter-spacing: 0.14em; color: var(--ink-soft);
  margin: 0 0 20px; padding-bottom: 12px; border-bottom: 1px solid var(--rule); }
.flow { margin: 0 0 16px; padding-left: 20px; display: grid; gap: 10px; max-width: 70ch; }

.site-foot { border-top: 1px solid var(--rule); padding-block: 24px 36px; font-size: 0.8rem; color: var(--ink-soft); }
.site-foot .container { display: flex; flex-wrap: wrap; justify-content: space-between; gap: 8px 24px; }

@media (max-width: 640px) {
  .container { padding-inline: 16px; }
  main { padding-block: 32px 56px; }
  .ask-form { flex-direction: column; }
  .btn { padding: 12px 18px; }
  .step, .answer { padding: 14px; }
  .trace .live-btn { margin-left: 0; }
}