:root {
  color-scheme: light;
  --page: #fffbef;
  --surface: #ffffff;
  --surface-raised: #ffffff;
  --surface-muted: #fff6e6;
  --ink: #282349;
  --ink-soft: #4f4a6b;
  --ink-muted: #6f6880;
  --line: #e7e2d5;
  --line-strong: #cfc8b8;
  --accent: #e34d36;
  --accent-dark: #ca3721;
  --accent-soft: #fde0de;
  --series-1: #e34d36;
  --series-2: #6b5fb5;
  --series-3: #b8860b;
  --warning: #b86100;
  --danger: #a92e1c;
  --success: #0f7a4a;
  --grid: #efe9dc;
  --shadow: 0 14px 42px rgba(40, 35, 73, 0.10);
  --radius: 14px;
  --font: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

:root[data-theme="dark"] {
  color-scheme: dark;
  --page: #17142a;
  --surface: #1f1b39;
  --surface-raised: #272247;
  --surface-muted: #272247;
  --ink: #f7f6fb;
  --ink-soft: #cbc7dc;
  --ink-muted: #9a95b3;
  --line: #3a3462;
  --line-strong: #524b82;
  --accent: #f4665c;
  --accent-dark: #ff8b83;
  --accent-soft: #3a2038;
  --series-1: #e34d36;
  --series-2: #8a7fc4;
  --series-3: #b8860b;
  --warning: #f1aa46;
  --danger: #f4665c;
  --success: #52c68e;
  --grid: #332d59;
  --shadow: 0 14px 42px rgba(0, 0, 0, 0.34);
}

* { box-sizing: border-box; }
[hidden] { display: none !important; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--page);
  color: var(--ink);
  font-family: var(--font);
  line-height: 1.5;
}
button, input, select { font: inherit; }
button, a { -webkit-tap-highlight-color: transparent; }
a { color: var(--accent-dark); text-underline-offset: 3px; }
button:focus-visible, a:focus-visible, input:focus-visible, select:focus-visible, summary:focus-visible, [tabindex="0"]:focus-visible {
  outline: 3px solid color-mix(in srgb, var(--accent) 45%, transparent);
  outline-offset: 3px;
}
.skip-link { position: fixed; left: 16px; top: -80px; z-index: 100; padding: 10px 16px; background: var(--surface); border-radius: 8px; }
.skip-link:focus { top: 16px; }

.site-header {
  max-width: 1500px;
  margin: 0 auto;
  min-height: 74px;
  padding: 0 32px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  border-bottom: 1px solid var(--line);
}
.site-header nav { display: flex; align-items: center; gap: 24px; }
.site-header nav a { color: var(--ink-soft); text-decoration: none; font-size: 14px; font-weight: 650; }
.brand { display: inline-flex; align-items: center; text-decoration: none; }
.brand img { display: block; width: auto; }
/* The two official lockups differ: the colour mark carries the tagline (591x134),
   the white one does not (591x76). Heights are set in that 1.76 ratio so the
   "ABsmartly" wordmark renders at the same optical size in both themes.
   Visibility is driven by the `hidden` ATTRIBUTE (toggled in app.js), not by a
   CSS-only rule, so a stale or missing stylesheet can never show both at once. */
.brand .logo-light { height: 42px; }
.brand .logo-dark { height: 24px; }
.icon-button { border: 1px solid var(--line); width: 36px; height: 36px; border-radius: 50%; background: var(--surface); color: var(--ink); cursor: pointer; }

.hero {
  max-width: 1100px;
  margin: 0 auto;
  text-align: center;
  padding: 104px 32px 86px;
}
.eyebrow { margin: 0 0 12px; color: var(--accent-dark); font-size: 12px; line-height: 1.2; font-weight: 800; letter-spacing: 0.13em; }
.hero h1 { margin: 0; font-size: clamp(44px, 7vw, 82px); line-height: 0.98; letter-spacing: -0.06em; }
.lede { max-width: 760px; margin: 30px auto 0; color: var(--ink-soft); font-size: clamp(18px, 2.2vw, 22px); }
.hero-actions { display: flex; justify-content: center; gap: 12px; margin-top: 34px; flex-wrap: wrap; }
.quiet { color: var(--ink-muted); font-size: 13px; margin-top: 18px; }

.button { border: 1px solid var(--line-strong); border-radius: 9px; padding: 11px 17px; background: var(--surface); color: var(--ink); cursor: pointer; font-weight: 720; }
.button:hover { border-color: var(--accent); }
.button-primary { background: var(--accent); border-color: var(--accent); color: #fff; box-shadow: 0 6px 18px color-mix(in srgb, var(--accent) 24%, transparent); }
.button-primary:hover { background: var(--accent-dark); }
.button-secondary { background: var(--surface); }
.button-compact { padding: 8px 11px; font-size: 12px; }
.button:disabled { opacity: .45; cursor: not-allowed; }
.text-button { border: 0; padding: 8px 2px; background: transparent; color: var(--accent-dark); cursor: pointer; font-weight: 650; }

.lab { max-width: 1500px; margin: 0 auto 110px; padding: 0 24px; }
.experiment-nav { display: grid; grid-template-columns: repeat(6, minmax(0, 1fr)); gap: 4px; padding: 5px; border: 1px solid var(--line); background: var(--surface-muted); border-radius: 12px 12px 0 0; }
.experiment-nav button { min-height: 52px; padding: 8px 10px; border: 0; border-radius: 8px; background: transparent; color: var(--ink-soft); cursor: pointer; font-size: 13px; font-weight: 680; }
.experiment-nav button[aria-selected="true"] { background: var(--surface); color: var(--ink); box-shadow: 0 2px 10px rgba(21,42,72,.08); }
.experiment-panel { display: grid; grid-template-columns: minmax(250px, 320px) 1fr; border: 1px solid var(--line); border-top: 0; background: var(--surface); border-radius: 0 0 var(--radius) var(--radius); box-shadow: var(--shadow); overflow: hidden; min-height: 680px; }
.controls { padding: 30px 26px; background: var(--surface-muted); border-right: 1px solid var(--line); }
.controls h2 { margin: 0; font-size: 22px; letter-spacing: -0.03em; }
.field { display: grid; gap: 6px; margin-top: 20px; }
.field-label-row { display: flex; align-items: center; justify-content: space-between; gap: 8px; }
.field label { font-size: 13px; font-weight: 720; color: var(--ink-soft); }
.help-toggle {
  flex: none; width: 20px; height: 20px; padding: 0; border-radius: 50%;
  border: 1px solid var(--line-strong); background: var(--surface);
  color: var(--ink-soft); font-size: 11px; font-weight: 800; line-height: 1; cursor: pointer;
}
.help-toggle:hover { border-color: var(--accent); color: var(--accent-dark); }
.help-toggle[aria-expanded="true"] { background: var(--accent); border-color: var(--accent); color: #fff; }
.field-help {
  margin: 2px 0 0; padding: 10px 12px; font-size: 12px; line-height: 1.5;
  color: var(--ink-soft); background: var(--surface); border: 1px solid var(--line);
  border-left: 3px solid var(--accent); border-radius: 0 8px 8px 0;
}
.help-all { margin-top: 4px; }
.field .hint { font-size: 11px; color: var(--ink-muted); }
.field input, .field select { width: 100%; height: 42px; border: 1px solid var(--line-strong); border-radius: 8px; background: var(--surface); color: var(--ink); padding: 7px 10px; }
.field-row { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; }
.control-actions { display: grid; gap: 9px; margin-top: 26px; }
/* No min-height: when there is nothing to report the row collapses instead of
   leaving a blank gap under "Reset defaults". */
.run-status { color: var(--ink-soft); font-size: 13px; }
.run-status:not(:empty) { margin-top: 20px; }
/* Visually hidden but still announced by screen readers. */
.sr-only {
  position: absolute; width: 1px; height: 1px; margin: -1px; padding: 0;
  overflow: hidden; clip: rect(0 0 0 0); clip-path: inset(50%); white-space: nowrap; border: 0;
}
progress { width: 100%; height: 8px; accent-color: var(--accent); }
.control-note { font-size: 11px; color: var(--ink-muted); margin-top: 18px; }

.results { min-width: 0; padding: 34px 38px 42px; }
.result-header { display: flex; justify-content: space-between; align-items: flex-start; gap: 24px; padding-bottom: 25px; border-bottom: 1px solid var(--line); }
.result-header h2 { margin: 0; font-size: clamp(26px, 3vw, 38px); letter-spacing: -0.04em; }
.result-header p:not(.eyebrow) { margin: 8px 0 0; color: var(--ink-soft); max-width: 720px; }
.result-actions { display: flex; gap: 7px; flex-wrap: wrap; justify-content: flex-end; }
.placeholder { min-height: 500px; display: grid; place-content: center; text-align: center; color: var(--ink-soft); }
.placeholder-number { margin: 0 auto 12px; display: grid; place-content: center; width: 72px; height: 72px; border-radius: 50%; background: var(--accent-soft); color: var(--accent-dark); font-size: 22px; font-weight: 800; }
.placeholder h3 { color: var(--ink); margin: 0; font-size: 22px; }
.placeholder p:last-child { margin: 8px 0; }
.stat-grid { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 12px; margin: 26px 0; }
.stat { padding: 20px; background: var(--surface-muted); border: 1px solid var(--line); border-radius: 10px; }
.stat-label { color: var(--ink-soft); font-size: 12px; font-weight: 700; }
.stat-value { margin-top: 5px; font-size: clamp(28px, 3vw, 42px); line-height: 1; letter-spacing: -0.04em; font-weight: 800; }
.stat-detail { color: var(--ink-muted); font-size: 11px; margin-top: 8px; }
.chart-region { display: grid; gap: 20px; }
.chart-card { border: 1px solid var(--line); border-radius: 10px; padding: 18px; min-width: 0; }
.chart-card h3 { margin: 0; font-size: 16px; }
.chart-card > p { margin: 4px 0 12px; color: var(--ink-muted); font-size: 12px; }
.chart-wrap { min-height: 280px; position: relative; }
.chart-wrap svg { display: block; width: 100%; height: auto; overflow: visible; }
.chart-grid { stroke: var(--grid); stroke-width: 1; }
.chart-axis { stroke: var(--line-strong); stroke-width: 1; }
.chart-label { fill: var(--ink-muted); font: 11px var(--font); }
.chart-direct-label { fill: var(--ink); font: 12px var(--font); font-weight: 700; }
.chart-line { fill: none; stroke-width: 2.4; stroke-linecap: round; stroke-linejoin: round; }
.chart-point { stroke: var(--surface); stroke-width: 3; cursor: pointer; }
.chart-hit { fill: transparent; cursor: pointer; }
.chart-bar { cursor: pointer; }
.legend { display: flex; flex-wrap: wrap; gap: 16px; margin: 10px 0 0; color: var(--ink-soft); font-size: 12px; }
.legend-item { display: inline-flex; align-items: center; gap: 7px; }
.legend-key { display: inline-block; width: 20px; height: 3px; border-radius: 2px; }
.small-multiples { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 10px; }
.interpretation { margin-top: 24px; padding: 22px; border-left: 4px solid var(--accent); background: var(--accent-soft); border-radius: 0 9px 9px 0; }
.interpretation h3 { margin: 0; font-size: 16px; }
.interpretation p { margin: 8px 0 0; }
.method-note { color: var(--ink-soft); font-size: 12px; }
.table-details { margin-top: 24px; border-top: 1px solid var(--line); padding-top: 18px; }
.table-details summary { cursor: pointer; color: var(--accent-dark); font-weight: 720; }
.table-scroll { margin-top: 12px; overflow-x: auto; }
table { border-collapse: collapse; width: 100%; font-size: 12px; font-variant-numeric: tabular-nums; }
th, td { padding: 10px 12px; text-align: right; border-bottom: 1px solid var(--line); white-space: nowrap; }
th { color: var(--ink-soft); font-weight: 750; background: var(--surface-muted); }
th:first-child, td:first-child { text-align: left; }
.tooltip { position: fixed; z-index: 50; pointer-events: none; max-width: 240px; padding: 9px 11px; border: 1px solid var(--line-strong); background: var(--surface-raised); color: var(--ink); border-radius: 7px; box-shadow: var(--shadow); font-size: 12px; }

.principles { max-width: 1200px; margin: 0 auto 110px; padding: 0 32px; }
.principles > h2 { max-width: 850px; margin: 0; font-size: clamp(34px, 5vw, 58px); line-height: 1.05; letter-spacing: -0.05em; }
.principle-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; margin-top: 40px; }
.principle-grid article { padding: 24px 0; border-top: 2px solid var(--line-strong); }
.principle-grid span { color: var(--accent-dark); font-size: 12px; font-weight: 800; }
.principle-grid h3 { margin: 12px 0 4px; font-size: 20px; }
.principle-grid p { color: var(--ink-soft); margin: 0; }
footer { max-width: 1500px; margin: 0 auto; border-top: 1px solid var(--line); padding: 28px 32px 46px; display: flex; justify-content: space-between; color: var(--ink-muted); font-size: 13px; }

@media (max-width: 1050px) {
  .experiment-nav { grid-template-columns: repeat(3, 1fr); }
  .experiment-panel { grid-template-columns: 1fr; }
  .controls { border-right: 0; border-bottom: 1px solid var(--line); }
  #simulation-form { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 0 14px; }
  .control-actions { grid-template-columns: repeat(3, minmax(0, 1fr)); }
}
@media (max-width: 720px) {
  .site-header { padding: 0 18px; }
  .site-header nav a { display: none; }
  .hero { padding: 72px 20px 58px; }
  .lab { padding: 0 10px; }
  .experiment-nav { grid-template-columns: repeat(2, 1fr); }
  .experiment-nav button { font-size: 11px; }
  .results { padding: 24px 18px 30px; }
  .result-header { display: block; }
  .result-actions { justify-content: flex-start; margin-top: 18px; }
  #simulation-form { grid-template-columns: 1fr 1fr; }
  .stat-grid, .small-multiples, .principle-grid { grid-template-columns: 1fr; }
  .principles { padding: 0 20px; }
  footer { display: block; padding: 24px 20px; }
}
@media (max-width: 480px) {
  #simulation-form { grid-template-columns: 1fr; }
  .control-actions { grid-template-columns: 1fr; }
  .field-row { grid-template-columns: 1fr; }
}
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { scroll-behavior: auto !important; transition: none !important; animation: none !important; }
}
@media print {
  .site-header, .controls, .result-actions, .hero-actions, .experiment-nav { display: none !important; }
  body { background: white; color: black; }
  .experiment-panel { display: block; border: 0; box-shadow: none; }
  .results { padding: 0; }
}