:root {
  color-scheme: dark;
  --bg: #07101f;
  --panel: #0d192b;
  --panel-soft: #111f34;
  --ink: #f4f8ff;
  --muted: #a7b5c9;
  --line: rgba(255, 255, 255, 0.12);
  --blue: #79b7ff;
  --cyan: #5ee9d1;
  --amber: #ffca72;
  --red: #ff8f94;
  --green: #83e6a3;
  --shadow: 0 24px 80px rgba(0, 0, 0, 0.28);
  font-family: Inter, ui-sans-serif, -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  background:
    radial-gradient(circle at 82% 8%, rgba(45, 113, 230, 0.22), transparent 32rem),
    radial-gradient(circle at 4% 43%, rgba(40, 185, 167, 0.11), transparent 29rem),
    var(--bg);
  color: var(--ink);
  line-height: 1.65;
}
a { color: inherit; }
button, select, input, a { -webkit-tap-highlight-color: transparent; }
.skip-link {
  position: fixed;
  left: 1rem;
  top: -5rem;
  z-index: 20;
  padding: .7rem 1rem;
  background: var(--ink);
  color: var(--bg);
  border-radius: .5rem;
}
.skip-link:focus { top: 1rem; }

.topbar {
  position: sticky;
  top: 0;
  z-index: 10;
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: 4.5rem;
  padding: 0 max(1.25rem, calc((100vw - 1180px) / 2));
  border-bottom: 1px solid var(--line);
  background: rgba(7, 16, 31, .86);
  backdrop-filter: blur(18px);
}
.brand {
  display: inline-flex;
  gap: .7rem;
  align-items: center;
  font-weight: 750;
  text-decoration: none;
  letter-spacing: -.02em;
}
.brand-mark {
  display: grid;
  place-items: center;
  width: 2rem;
  aspect-ratio: 1;
  border-radius: .65rem;
  color: #06111f;
  background: linear-gradient(135deg, var(--cyan), var(--blue));
}
nav { display: flex; align-items: center; gap: 1.4rem; }
nav a { color: var(--muted); text-decoration: none; font-size: .92rem; }
nav a:hover, nav a:focus-visible { color: var(--ink); }
.repo-link { padding: .45rem .75rem; border: 1px solid var(--line); border-radius: .6rem; }

main, footer { width: min(1180px, calc(100% - 2.5rem)); margin-inline: auto; }
.hero {
  min-height: 42rem;
  display: grid;
  grid-template-columns: 1.32fr .68fr;
  gap: 4.5rem;
  align-items: center;
  padding: 6.5rem 0 4rem;
}
.eyebrow { margin: 0 0 .7rem; color: var(--cyan); font-size: .74rem; font-weight: 750; letter-spacing: .14em; }
h1, h2, h3, p { margin-top: 0; }
h1 { max-width: 13ch; margin-bottom: 1.4rem; font-size: clamp(2.8rem, 5.8vw, 5.35rem); line-height: 1.03; letter-spacing: -.055em; }
h2 { font-size: clamp(2rem, 3.5vw, 3.25rem); line-height: 1.12; letter-spacing: -.04em; }
h3 { font-size: 1.3rem; line-height: 1.3; letter-spacing: -.018em; }
.lede { max-width: 45rem; color: #c9d5e6; font-size: 1.14rem; }
.hero-actions, .replay-controls, .evidence-actions { display: flex; flex-wrap: wrap; gap: .8rem; align-items: center; }
.button {
  display: inline-flex;
  justify-content: center;
  align-items: center;
  min-height: 2.85rem;
  padding: .65rem 1.05rem;
  border: 1px solid transparent;
  border-radius: .75rem;
  font: inherit;
  font-weight: 700;
  text-decoration: none;
  cursor: pointer;
}
.button.primary { background: var(--ink); color: var(--bg); }
.button.primary:hover { background: var(--cyan); }
.button.secondary { color: var(--ink); background: transparent; border-color: var(--line); }
.button.secondary:hover { border-color: var(--blue); }
.button.wide { width: 100%; }
.button:focus-visible, .scenario-tab:focus-visible, .text-button:focus-visible, a:focus-visible, select:focus-visible, input:focus-visible {
  outline: 3px solid rgba(121, 183, 255, .55);
  outline-offset: 3px;
}
.hero-proof { padding: 1.8rem; border: 1px solid var(--line); border-radius: 1.25rem; background: rgba(13, 25, 43, .82); box-shadow: var(--shadow); }
.hero-proof-label { color: var(--muted); font-size: .82rem; }
.hero-proof ol { list-style: none; margin: 0; padding: 0; }
.hero-proof li { display: grid; grid-template-columns: 2.4rem 1fr; align-items: center; gap: .8rem; padding: .9rem 0; border-top: 1px solid var(--line); }
.hero-proof li span { color: var(--cyan); font: 700 .76rem ui-monospace, SFMono-Regular, Menlo, monospace; }

.problem-section, .lab-section, .demo-section, .evidence-section, .boundary-section { padding: 7.5rem 0 1rem; }
.section-heading { display: flex; justify-content: space-between; align-items: end; gap: 3rem; margin-bottom: 2.2rem; }
.section-heading h2 { max-width: 18ch; margin-bottom: 0; }
.section-heading > p { max-width: 31rem; margin-bottom: .4rem; color: var(--muted); }
.problem-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 1rem; }
.problem-grid article { min-height: 16rem; padding: 1.55rem; border: 1px solid var(--line); border-radius: 1rem; background: linear-gradient(150deg, rgba(17,31,52,.9), rgba(13,25,43,.66)); }
.problem-grid p { color: var(--muted); }
.problem-number { display: block; margin-bottom: 2.4rem; color: var(--blue); font: 700 .8rem ui-monospace, SFMono-Regular, Menlo, monospace; }

.solution-strip { display: flex; justify-content: space-between; gap: 1rem; margin-top: 4rem; padding: 1.15rem 1.4rem; border-block: 1px solid var(--line); color: #b9c8db; font-size: .86rem; }
.solution-strip strong { color: var(--ink); }
.solution-strip b { color: #51647e; }

.lab-grid { display: grid; grid-template-columns: .82fr 1.18fr; gap: 1rem; align-items: stretch; }
.lab-controls, .decision-panel, .passport-panel { padding: 1.5rem; border: 1px solid var(--line); border-radius: 1.1rem; background: rgba(13,25,43,.84); }
.lab-controls { grid-row: span 2; }
.lab-controls fieldset { margin: 0 0 1.25rem; padding: 0; border: 0; }
.lab-controls legend, .lab-controls label > span:first-child { display: block; margin-bottom: .55rem; color: #dce7f5; font-size: .82rem; font-weight: 700; }
.control-row { display: grid; grid-template-columns: 1fr 1fr; gap: .8rem; margin-bottom: 1.25rem; }
.lab-controls > label { display: block; margin-bottom: 1.25rem; }
select { width: 100%; min-height: 2.8rem; padding: .6rem .75rem; border: 1px solid var(--line); border-radius: .7rem; background: #081323; color: var(--ink); font: inherit; }
.segmented, .mutation-grid { display: grid; gap: .55rem; }
.segmented { grid-template-columns: 1fr 1fr; }
.mutation-grid { grid-template-columns: repeat(2, 1fr); }
.segmented label, .mutation-grid label { cursor: pointer; }
.segmented input, .mutation-grid input { position: absolute; opacity: 0; pointer-events: none; }
.segmented label span, .mutation-grid label span { display: grid; place-items: center; min-height: 2.75rem; margin: 0; padding: .5rem; border: 1px solid var(--line); border-radius: .7rem; color: var(--muted); font-size: .86rem; }
.segmented input:checked + span, .mutation-grid input:checked + span { border-color: var(--blue); color: var(--ink); background: rgba(60,121,217,.18); }
select:disabled { opacity: .48; cursor: not-allowed; }
.form-note { margin: .75rem 0 0; color: #72839a; font-size: .74rem; }

.decision-panel { min-height: 24rem; }
.decision-panel[data-tone="green"] { border-color: rgba(131,230,163,.36); }
.decision-panel[data-tone="cyan"] { border-color: rgba(94,233,209,.36); }
.decision-panel[data-tone="amber"] { border-color: rgba(255,202,114,.38); }
.decision-panel[data-tone="red"] { border-color: rgba(255,143,148,.4); }
.decision-head, .replay-head, .evidence-head { display: flex; justify-content: space-between; gap: 1rem; align-items: start; }
.decision-badge, .terminal-badge, .integrity-badge { flex: 0 0 auto; padding: .32rem .6rem; border: 1px solid var(--line); border-radius: 999px; color: var(--cyan); font: 700 .72rem ui-monospace, SFMono-Regular, Menlo, monospace; }
.decision-summary { color: var(--muted); }
.decision-steps { list-style: none; margin: 1.35rem 0; padding: 0; }
.decision-steps li { position: relative; padding: 0 0 1rem 1.8rem; border-left: 1px solid #29405f; }
.decision-steps li::before { content: ""; position: absolute; left: -.33rem; top: .25rem; width: .6rem; height: .6rem; border-radius: 50%; background: var(--blue); }
.decision-steps li.warn::before { background: var(--amber); }
.decision-steps li.blocked::before { background: var(--red); }
.decision-steps strong { display: block; }
.decision-steps span { color: var(--muted); font-size: .87rem; }
.decision-footer { display: grid; grid-template-columns: .75fr .75fr 1.5fr; gap: .55rem; }
.decision-footer div { min-width: 0; padding: .75rem; border: 1px solid var(--line); border-radius: .75rem; background: rgba(7,16,31,.6); }
.decision-footer span { display: block; color: var(--muted); font-size: .7rem; }
.decision-footer strong { display: block; overflow: hidden; color: var(--ink); font-size: .95rem; text-overflow: ellipsis; white-space: nowrap; }

.passport-panel { grid-column: 2; }
.passport-panel > p { color: var(--muted); }
.passport-panel dl { display: grid; grid-template-columns: repeat(3, 1fr); gap: .55rem; }
.passport-panel dl div { min-width: 0; padding: .65rem; border-bottom: 1px solid var(--line); }
.passport-panel dt { color: var(--muted); font-size: .7rem; }
.passport-panel dd { margin: .1rem 0 0; overflow: hidden; font-size: .78rem; font-weight: 700; text-overflow: ellipsis; white-space: nowrap; }
.passport-panel pre, .evidence-panel pre { overflow: auto; margin: 1rem 0 0; padding: 1rem; border-radius: .8rem; background: #07101f; color: #bed3ec; font: .75rem/1.6 ui-monospace, SFMono-Regular, Menlo, Consolas, monospace; white-space: pre-wrap; word-break: break-word; }
.passport-panel pre { max-height: 15rem; }

.scenario-tabs { display: grid; grid-template-columns: repeat(3, 1fr); gap: .7rem; margin-bottom: 1rem; }
.scenario-tab { min-height: 4.9rem; padding: .9rem 1rem; border: 1px solid var(--line); border-radius: .9rem; background: rgba(13,25,43,.7); color: var(--muted); text-align: left; font: inherit; cursor: pointer; }
.scenario-tab strong { display: block; margin-bottom: .15rem; color: var(--ink); }
.scenario-tab[aria-selected="true"] { border-color: var(--blue); background: rgba(60,121,217,.16); color: #d8e8ff; }
.replay-grid { display: grid; grid-template-columns: 1.05fr .95fr; gap: 1rem; }
.replay-panel, .evidence-panel { min-height: 34rem; padding: 1.6rem; border: 1px solid var(--line); border-radius: 1.15rem; background: rgba(13,25,43,.82); }
.case-id { margin-bottom: .15rem; color: var(--muted); font: 600 .78rem ui-monospace, SFMono-Regular, Menlo, monospace; }
.scenario-summary { color: var(--muted); }
.timeline { list-style: none; margin: 1.5rem 0; padding: 0; }
.timeline li { position: relative; margin-left: .6rem; padding: 0 0 1.05rem 2.1rem; color: #74849b; border-left: 1px solid #263751; }
.timeline li::before { content: ""; position: absolute; left: -.38rem; top: .2rem; width: .7rem; height: .7rem; border-radius: 50%; background: #31445f; }
.timeline li strong { display: block; color: #77889f; }
.timeline li.done { color: #c1cede; }
.timeline li.done strong { color: var(--ink); }
.timeline li.done::before { background: var(--cyan); }
.timeline li.current { color: #dce9f8; }
.timeline li.current::before { background: var(--amber); box-shadow: 0 0 0 .32rem rgba(255,202,114,.12); }
.evidence-panel pre { min-height: 15rem; max-height: 20rem; }
.fact-list { display: grid; grid-template-columns: 1fr 1fr; gap: .5rem 1rem; margin: 1rem 0; }
.fact-list div { padding: .65rem 0; border-bottom: 1px solid var(--line); }
.fact-list dt { color: var(--muted); font-size: .75rem; }
.fact-list dd { margin: .08rem 0 0; font-weight: 700; }
.text-link, .text-button { color: var(--blue); font-size: .86rem; }
.text-button { border: 0; background: none; font: inherit; cursor: pointer; padding: 0; }

.metric-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: .8rem; }
.metric-card { padding: 1.25rem; border: 1px solid var(--line); border-radius: 1rem; background: var(--panel); }
.metric-card .question { min-height: 3.2rem; color: #d7e1ef; }
.metric-card strong { display: block; margin: .6rem 0 .2rem; font-size: 2rem; letter-spacing: -.04em; }
.metric-card p:last-child { margin-bottom: 0; color: var(--muted); font-size: .86rem; }
.agentteams-card { display: grid; grid-template-columns: 1.2fr .8fr; gap: 2rem; margin-top: 1rem; padding: 1.7rem; border: 1px solid rgba(94,233,209,.25); border-radius: 1rem; background: linear-gradient(135deg, rgba(28,78,87,.3), rgba(13,25,43,.85)); }
.agentteams-card p { color: var(--muted); }
.runtime-facts { display: grid; grid-template-columns: repeat(3,1fr); gap: .5rem; align-items: center; }
.runtime-facts span { padding: 1rem .6rem; text-align: center; color: var(--muted); font-size: .72rem; border-left: 1px solid var(--line); }
.runtime-facts strong { display: block; color: var(--ink); font-size: 1.35rem; }

.boundary-section { display: grid; grid-template-columns: .75fr 1.25fr; gap: 4rem; padding-bottom: 7rem; }
.boundary-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 1rem; }
.boundary-grid article { padding: 1.35rem; border: 1px solid var(--line); border-radius: 1rem; background: var(--panel); }
.boundary-grid ul { margin: 0; padding-left: 1.1rem; color: var(--muted); }
.boundary-grid li + li { margin-top: .45rem; }
footer { display: flex; justify-content: space-between; gap: 2rem; padding: 1.5rem 0 2rem; color: #75869d; border-top: 1px solid var(--line); font-size: .8rem; }
footer p { margin: 0; }
noscript { display: block; padding: 1rem; background: var(--amber); color: #251500; text-align: center; }

@media (max-width: 960px) {
  nav a:not(.repo-link) { display: none; }
  .hero { grid-template-columns: 1fr; gap: 2rem; min-height: auto; }
  .hero-proof { max-width: 40rem; }
  .solution-strip { overflow-x: auto; justify-content: start; white-space: nowrap; }
  .lab-grid, .replay-grid, .agentteams-card, .boundary-section { grid-template-columns: 1fr; }
  .lab-controls { grid-row: auto; }
  .passport-panel { grid-column: auto; }
  .metric-grid { grid-template-columns: 1fr 1fr; }
}

@media (max-width: 680px) {
  main, footer { width: min(100% - 1.4rem, 1180px); }
  .topbar { padding-inline: .8rem; }
  .hero { padding-top: 4rem; }
  h1 { font-size: 2.7rem; }
  .section-heading { display: block; }
  .problem-grid, .scenario-tabs, .metric-grid, .boundary-grid, .control-row { grid-template-columns: 1fr; }
  .segmented, .mutation-grid { grid-template-columns: 1fr 1fr; }
  .decision-footer, .passport-panel dl { grid-template-columns: 1fr; }
  .replay-panel, .evidence-panel, .lab-controls, .decision-panel, .passport-panel { padding: 1rem; }
  .fact-list, .runtime-facts { grid-template-columns: 1fr; }
  .runtime-facts span { border-left: 0; border-top: 1px solid var(--line); }
  footer { display: block; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
}