:root {
  color-scheme: dark;
  --page: #08100f;
  --surface: #101a18;
  --surface-raised: #16231f;
  --line: #587268;
  --line-soft: #263832;
  --text: #f2f7f4;
  --muted: #aebdb6;
  --accent: #84efbf;
  --accent-deep: #1a7a58;
  --warning: #ffc37a;
  --source: #84efbf;
  --target: #ffc37a;
  --radius: 16px;
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

* { box-sizing: border-box; }

html { background: var(--page); scroll-behavior: smooth; }

body {
  margin: 0;
  background:
    radial-gradient(circle at 78% -10%, rgb(132 239 191 / 10%), transparent 38rem),
    var(--page);
  color: var(--text);
  font-size: 1rem;
  line-height: 1.5;
}

button, input { font: inherit; }

button {
  min-height: 44px;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: transparent;
  color: var(--text);
  cursor: pointer;
  transition: border-color 180ms ease-out, background-color 180ms ease-out, transform 180ms ease-out;
}

button:hover { border-color: var(--accent); }
button:active { transform: translateY(1px); }
button[aria-pressed="true"], button.primary { background: var(--accent); border-color: var(--accent); color: #07130f; }
button:disabled { cursor: not-allowed; opacity: 0.7; }

:focus-visible { outline: 3px solid var(--warning); outline-offset: 3px; }

.skip-link {
  position: fixed;
  z-index: 20;
  top: 12px;
  left: 12px;
  transform: translateY(-180%);
  padding: 10px 14px;
  border-radius: 8px;
  background: var(--warning);
  color: #181006;
}
.skip-link:focus { transform: translateY(0); }

main { width: min(1480px, 100%); margin: 0 auto; padding: 64px 24px 80px; }

.hero {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  gap: 64px;
  align-items: end;
  padding-bottom: 48px;
  border-bottom: 1px solid var(--line);
}

.eyebrow, .section-kicker, .panel-kicker {
  margin: 0 0 8px;
  color: var(--accent);
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.11em;
  text-transform: uppercase;
}

h1, h2, p { margin-top: 0; }
h1 { margin-bottom: 8px; font-size: clamp(2.8rem, 7vw, 6.5rem); line-height: 0.95; letter-spacing: -0.065em; }
h2 { margin-bottom: 0; font-size: clamp(1.25rem, 2vw, 1.75rem); line-height: 1.2; letter-spacing: -0.025em; }
.lede { margin-bottom: 8px; color: var(--muted); font-size: clamp(1.25rem, 2vw, 1.8rem); }
.intro { max-width: 66ch; margin-bottom: 0; color: var(--muted); }
.intro strong { color: var(--text); font-weight: 700; }

.concept-pair {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 24px;
  max-width: 760px;
  margin: 24px 0 0;
}
.concept-pair div { padding-left: 16px; border-left: 2px solid var(--line); }
.concept-pair dt { font-weight: 700; }
.concept-pair dd { margin: 4px 0 0; color: var(--muted); font-size: 0.9rem; }

.hero-reading { min-width: 220px; text-align: right; }
.reading-label, .hero-reading span { display: block; color: var(--muted); }
.hero-reading strong { display: block; margin: 2px 0; font-size: 2.4rem; line-height: 1; }

.controls-section, .metrics-section { padding: 48px 0; border-bottom: 1px solid var(--line); }
.section-heading { display: flex; justify-content: space-between; gap: 48px; align-items: end; margin-bottom: 32px; }
.section-note { max-width: 52ch; margin-bottom: 0; color: var(--muted); }

.comparison-cue {
  display: flex;
  align-items: center;
  gap: 12px;
  margin: -8px 0 24px;
  color: var(--muted);
}
.comparison-label {
  padding: 4px 8px;
  border-radius: 6px;
  background: var(--accent);
  color: #07130f;
  font-size: 0.78rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
}
.comparison-cue strong { color: var(--text); }
.comparison-arrow { color: var(--accent); font-size: 1.4rem; line-height: 1; }
.comparison-note { margin-left: 4px; }

.control-grid { display: grid; grid-template-columns: 1.25fr 1.1fr minmax(230px, 0.8fr); gap: 24px; align-items: end; }
fieldset { min-width: 0; margin: 0; padding: 0; border: 0; }
legend, label { display: block; margin-bottom: 8px; color: var(--muted); font-size: 0.9rem; }
.segmented { display: grid; grid-template-columns: repeat(3, 1fr); gap: 8px; }
.graph-segments { grid-template-columns: repeat(4, 1fr); }
.segmented button { padding: 9px 12px; }
.segmented button span, .segmented button small { display: block; }
.segmented button small { margin-top: 1px; opacity: 0.75; font-size: 0.72rem; }

.layer-control input { width: 100%; accent-color: var(--accent); }
.transport { grid-column: 1 / -1; display: flex; gap: 8px; }
.transport button { padding: 8px 18px; }
.transport #edit-button { margin-left: auto; }

.workspace { display: grid; grid-template-columns: minmax(0, 2.1fr) minmax(290px, 0.85fr); gap: 24px; padding: 48px 0; border-bottom: 1px solid var(--line); }
.graph-panel, .explanation-panel, .metric-card { background: var(--surface); border: 1px solid var(--line-soft); border-radius: var(--radius); }
.graph-panel { overflow: hidden; }
.panel-heading { display: flex; justify-content: space-between; gap: 24px; align-items: start; padding: 24px; }
.legend { display: flex; flex-wrap: wrap; gap: 16px; color: var(--muted); font-size: 0.78rem; }
.legend span { display: flex; align-items: center; gap: 6px; }
.legend i { width: 10px; height: 10px; border-radius: 50%; background: var(--accent); }
.legend .source-dot { outline: 2px solid var(--source); outline-offset: 2px; background: transparent; }
.legend .target-dot { outline: 2px dashed var(--target); outline-offset: 2px; background: transparent; }

.graph-stage { position: relative; min-height: 420px; background: #050a09; border-top: 1px solid var(--line-soft); border-bottom: 1px solid var(--line-soft); }
#graph-svg { display: block; width: 100%; height: auto; min-height: 420px; }
.graph-edge { stroke: #3d534b; stroke-width: 3; vector-effect: non-scaling-stroke; }
.graph-node circle { stroke: #b7cbc2; stroke-width: 2; vector-effect: non-scaling-stroke; }
.graph-node text { fill: #06100c; font-size: 13px; font-weight: 800; text-anchor: middle; pointer-events: none; }
.graph-node.source circle { stroke: var(--source); stroke-width: 5; }
.graph-node.target circle { stroke: var(--target); stroke-width: 5; stroke-dasharray: 6 4; }
.graph-node.pending circle { stroke: #ffffff; stroke-width: 7; }
.graph-node[role="button"] { cursor: pointer; }
.graph-node[role="button"]:focus-visible { outline: none; }
.graph-node[role="button"]:focus-visible circle { stroke: var(--warning); stroke-width: 8; }

.edit-instruction { position: absolute; left: 24px; bottom: 20px; padding: 10px 14px; border: 1px solid var(--warning); border-radius: 8px; background: #15110a; color: #ffe5c1; }
.state-strip { display: flex; justify-content: space-between; gap: 16px; padding: 12px 24px; color: var(--muted); font-size: 0.82rem; }

.explanation-panel { padding: 28px; }
.explanation-panel > p:not(.panel-kicker, .equation-note) { margin-top: 16px; color: var(--muted); }
.equation { display: flex; gap: 10px; align-items: center; justify-content: center; margin-top: 32px; padding: 24px 12px; border-block: 1px solid var(--line-soft); font-family: ui-monospace, SFMono-Regular, Menlo, monospace; font-size: 1.1rem; }
.equation-note { margin: 12px 0 32px; color: var(--muted); font-size: 0.85rem; }
.topology-stats { display: grid; grid-template-columns: 1fr 1fr; gap: 8px; }
.topology-stats div { padding: 14px; background: var(--surface-raised); border-radius: 10px; }
.topology-stats span, .topology-stats strong { display: block; }
.topology-stats span { color: var(--muted); font-size: 0.78rem; }
.topology-stats strong { margin-top: 3px; font-size: 1.2rem; }

.compact-heading { margin-bottom: 24px; }
.metric-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 16px; }
.metric-card { padding: 20px; }
.metric-heading { display: flex; justify-content: space-between; gap: 16px; }
.metric-heading span { color: var(--muted); }
.metric-card p { margin-bottom: 0; color: var(--muted); font-size: 0.86rem; }
.chart { display: block; width: 100%; margin: 12px 0 8px; overflow: visible; }
.chart-baseline { fill: none; stroke: var(--line); stroke-width: 1; }
.chart-line { fill: none; stroke: var(--accent); stroke-width: 3; vector-effect: non-scaling-stroke; }
.chart-guide { stroke: var(--warning); stroke-width: 1; stroke-dasharray: 4 4; }
.chart-marker { fill: var(--warning); stroke: #1c1205; stroke-width: 2; }

.evidence-section { display: grid; grid-template-columns: 0.9fr 1.1fr; gap: 64px; padding: 48px 0 0; }
.evidence-copy p { max-width: 66ch; color: var(--muted); }
.evidence-copy a { color: var(--accent); text-underline-offset: 4px; }

@media (max-width: 980px) {
  .control-grid { grid-template-columns: 1fr 1fr; }
  .layer-control { grid-column: 1 / -1; }
  .workspace { grid-template-columns: 1fr; }
  .metric-grid { grid-template-columns: 1fr; }
}

@media (max-width: 620px) {
  main { padding: 32px 16px 56px; }
  .hero { grid-template-columns: 1fr; gap: 32px; align-items: start; padding-bottom: 32px; }
  .hero-reading { min-width: 0; text-align: left; }
  .controls-section, .metrics-section, .workspace { padding: 32px 0; }
  .section-heading, .panel-heading { display: block; }
  .section-note, .legend { margin-top: 16px; }
  .concept-pair { grid-template-columns: 1fr; gap: 16px; }
  .comparison-cue { align-items: flex-start; flex-wrap: wrap; margin-top: 0; }
  .comparison-note { flex-basis: 100%; margin: 0; }
  .control-grid { grid-template-columns: 1fr; }
  .layer-control { grid-column: auto; }
  .graph-segments { grid-template-columns: 1fr 1fr; }
  .segmented { grid-template-columns: 1fr; }
  .transport { grid-column: auto; flex-wrap: wrap; }
  .transport #edit-button { width: 100%; margin-left: 0; }
  .graph-stage, #graph-svg { min-height: 320px; }
  .state-strip { flex-direction: column; gap: 2px; }
  .evidence-section { grid-template-columns: 1fr; gap: 24px; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { scroll-behavior: auto !important; transition-duration: 0.01ms !important; animation-duration: 0.01ms !important; }
}