:root {
  color-scheme: light dark;

  /* Warm palette; accent tuned to Laredo amber. */
  --bg: hsl(30, 20%, 99%);
  --bg-subtle: hsl(30, 15%, 96%);
  --bg-muted: hsl(30, 12%, 93%);
  --fg: hsl(20, 10%, 15%);
  --fg-secondary: hsl(20, 5%, 38%);
  --fg-muted: hsl(20, 5%, 52%);
  --fg-faint: hsl(20, 5%, 68%);
  --border: hsl(30, 15%, 86%);
  --border-light: hsl(30, 15%, 92%);
  --accent: hsl(28, 84%, 38%);
  --accent-light: hsl(28, 70%, 94%);

  /* semantic diagram colours (mirrors viz.css) */
  --main: hsl(28, 84%, 48%);
  --main-soft: hsl(28, 85%, 94%);
  --canary: hsl(212, 72%, 50%);
  --canary-soft: hsl(212, 75%, 94%);
  --allow: hsl(150, 55%, 38%);
  --allow-soft: hsl(150, 50%, 93%);
  --queue: hsl(40, 92%, 46%);
  --queue-soft: hsl(40, 90%, 92%);
  --reject: hsl(2, 72%, 52%);
  --reject-soft: hsl(2, 75%, 95%);
  --sensitive: hsl(270, 45%, 50%);
  --sensitive-soft: hsl(270, 50%, 95%);

  --sans: -apple-system, BlinkMacSystemFont, "Segoe UI", system-ui, "Helvetica Neue", Arial, sans-serif;
  --display: "Charter", "Iowan Old Style", "Source Serif Pro", "Cambria", Georgia, serif;
  --mono: ui-monospace, SFMono-Regular, "JetBrains Mono", "Menlo", "Roboto Mono", monospace;

  --shadow-sm: 0 1px 2px hsl(30 20% 20% / 0.04);
  --shadow: 0 2px 4px hsl(30 20% 20% / 0.05), 0 4px 12px hsl(30 20% 20% / 0.04);
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: hsl(20, 8%, 10%);
    --bg-subtle: hsl(20, 6%, 13%);
    --bg-muted: hsl(20, 6%, 17%);
    --fg: hsl(30, 18%, 92%);
    --fg-secondary: hsl(20, 8%, 70%);
    --fg-muted: hsl(20, 8%, 56%);
    --fg-faint: hsl(20, 8%, 42%);
    --border: hsl(20, 6%, 24%);
    --border-light: hsl(20, 6%, 19%);
    --accent: hsl(35, 90%, 60%);
    --accent-light: hsl(28, 40%, 20%);
    --main: hsl(35, 88%, 60%);
    --main-soft: hsl(28, 40%, 22%);
    --canary: hsl(212, 80%, 64%);
    --canary-soft: hsl(212, 45%, 24%);
    --allow: hsl(150, 55%, 54%);
    --allow-soft: hsl(150, 30%, 20%);
    --queue: hsl(42, 90%, 58%);
    --queue-soft: hsl(42, 40%, 22%);
    --reject: hsl(2, 75%, 64%);
    --reject-soft: hsl(2, 40%, 24%);
    --sensitive: hsl(270, 60%, 72%);
    --sensitive-soft: hsl(270, 30%, 24%);
    --shadow-sm: 0 1px 2px hsl(0 0% 0% / 0.30);
    --shadow: 0 2px 4px hsl(0 0% 0% / 0.30), 0 4px 12px hsl(0 0% 0% / 0.25);
  }
}

* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
html { -webkit-text-size-adjust: 100%; }

body {
  font-family: var(--sans);
  background: var(--bg);
  color: var(--fg);
  font-size: 16px;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  font-feature-settings: "kern" 1, "liga" 1, "calt" 1;
  text-rendering: optimizeLegibility;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

::selection { background: var(--accent-light); color: var(--fg); }

.container { max-width: 1180px; margin: 0 auto; padding: 0 1.5rem; width: 100%; }

a {
  color: var(--accent);
  text-decoration: underline;
  text-decoration-color: hsl(from var(--accent) h s l / 0.35);
  text-underline-offset: 2px;
  transition: text-decoration-color 0.12s ease;
}
a:hover { text-decoration-color: var(--accent); }

/* Site header */
.site-header {
  border-bottom: 1px solid var(--border-light);
  background: var(--bg);
  padding: 1rem 0;
  font-size: 0.875rem;
  position: sticky;
  top: 0;
  z-index: 20;
}
.site-header .container { display: flex; align-items: center; justify-content: space-between; gap: 1rem; }
.site-header .brand {
  font-family: var(--mono); font-weight: 600; font-size: 0.95rem;
  letter-spacing: 0.01em; color: var(--fg); text-decoration: none;
}
.site-header .brand:hover { color: var(--accent); }
.site-header nav { display: flex; flex-wrap: wrap; gap: 0.25rem 1.25rem; }
.site-header nav a {
  font-family: var(--mono); font-size: 0.8rem; color: var(--fg-muted);
  text-decoration: none; letter-spacing: 0.02em;
}
.site-header nav a:hover { color: var(--accent); }
.site-header nav a.active { color: var(--accent); font-weight: 600; }

main.container { flex: 1; }

/* Site footer */
.site-footer {
  border-top: 1px solid var(--border-light);
  background: var(--bg-subtle);
  padding: 1.5rem 0;
  color: var(--fg-muted);
  font-size: 0.825rem;
  margin-top: 4rem;
}
.site-footer p { margin: 0; }
.site-footer a { color: var(--fg-secondary); }
.site-footer a:hover { color: var(--accent); }

/* ---- Doc shell: left sidebar + content ---- */
.doc-shell { display: block; padding-top: 1.5rem; }
@media (min-width: 900px) {
  .doc-shell { display: grid; grid-template-columns: 232px minmax(0, 1fr); gap: 3rem; }
}
.sidebar { min-width: 0; }
@media (min-width: 900px) {
  .sidebar { position: sticky; top: 4.5rem; align-self: start; max-height: calc(100vh - 5.5rem); overflow-y: auto; padding-bottom: 2rem; }
}
.sidebar .sb-group { margin-bottom: 1.4rem; }
.sidebar .sb-label {
  font-family: var(--mono); font-size: 0.68rem; font-weight: 600; text-transform: uppercase;
  letter-spacing: 0.06em; color: var(--fg-faint); margin: 0 0 0.5rem;
}
.sidebar ul { list-style: none; margin: 0; padding: 0; }
.sidebar li { margin: 0; }
.sidebar li a {
  display: block; padding: 0.28rem 0.6rem; border-radius: 6px;
  font-size: 0.875rem; color: var(--fg-secondary); text-decoration: none; line-height: 1.4;
}
.sidebar li a:hover { background: var(--bg-subtle); color: var(--fg); }
.sidebar li a.active { background: var(--accent-light); color: var(--accent); font-weight: 600; }

/* EDR / doc page */
.edr { padding: 3rem 0 2rem; }
.doc.edr { padding: 0 0 2rem; }

@media (min-width: 1140px) {
  .edr-layout {
    display: grid;
    grid-template-columns: minmax(0, 1fr) 200px;
    gap: 3rem;
    align-items: start;
  }
}
.edr-main { min-width: 0; }

.back { margin: 0 0 1.5rem; font-family: var(--mono); font-size: 0.8rem; }
.back a { color: var(--fg-muted); text-decoration: none; display: inline-flex; align-items: center; gap: 0.4rem; }
.back a:hover { color: var(--fg); }

.edr-header { margin-bottom: 2rem; }
.edr-id {
  display: inline-block; font-family: var(--mono); font-size: 0.8rem; color: var(--fg-muted);
  letter-spacing: 0.05em; margin-right: 0.75rem; vertical-align: middle;
}
.edr-header h1 {
  font-family: var(--display); font-size: 2.3rem; font-weight: 600;
  letter-spacing: -0.022em; line-height: 1.12; margin: 0.5rem 0 1rem; color: var(--fg);
}
@media (min-width: 768px) { .edr-header h1 { font-size: 2.7rem; } }

.edr-meta { display: flex; flex-wrap: wrap; gap: 1.5rem 2rem; margin: 0; font-size: 0.875rem; }
.edr-meta > div { margin: 0; }
.edr-meta dt {
  font-family: var(--mono); font-size: 0.72rem; font-weight: 500; color: var(--fg-faint);
  text-transform: uppercase; letter-spacing: 0.05em; margin-bottom: 0.25rem;
}
.edr-meta dd { margin: 0; color: var(--fg-secondary); }

.relations {
  list-style: none; padding: 0.9rem 1.1rem; margin: 1.75rem 0 0; background: var(--bg-subtle);
  border: 1px solid var(--border-light); border-radius: 8px; font-size: 0.9rem;
}
.relations li { margin: 0.2rem 0; color: var(--fg-secondary); }
.relations li a { color: var(--accent); }

/* Body content */
.edr-body { font-size: 1rem; line-height: 1.7; color: var(--fg-secondary); margin-top: 2rem; }
.edr-body > *:first-child { margin-top: 0; }
.edr-body h2 {
  font-family: var(--sans); font-size: 1.5rem; font-weight: 600; letter-spacing: -0.012em;
  color: var(--fg); margin: 2.75rem 0 1rem; padding-bottom: 0.5rem;
  border-bottom: 1px solid var(--border-light); scroll-margin-top: 5rem;
}
.edr-body h3 { font-family: var(--sans); font-size: 1.15rem; font-weight: 600; color: var(--fg); margin: 2rem 0 0.5rem; scroll-margin-top: 5rem; }
.edr-body h4 { font-family: var(--sans); font-size: 1rem; font-weight: 600; color: var(--fg); margin: 1.5rem 0 0.5rem; scroll-margin-top: 5rem; }
.edr-body h2 .heading-link, .edr-body h3 .heading-link, .edr-body h4 .heading-link { color: inherit; text-decoration: none; }
.edr-body h2 .heading-link:hover, .edr-body h3 .heading-link:hover, .edr-body h4 .heading-link:hover { color: var(--accent); }
.edr-body p { margin: 0.75rem 0; }
.edr-body ul, .edr-body ol { padding-left: 1.5rem; margin: 0.75rem 0; }
.edr-body li { margin: 0.3rem 0; }
.edr-body li > p:first-child { margin-top: 0; }
.edr-body li > p:last-child { margin-bottom: 0; }
.edr-body strong { font-weight: 600; color: var(--fg); }
.edr-body em { font-style: italic; }
.edr-body blockquote { border-left: 3px solid var(--accent); margin: 1.25rem 0; padding: 0.25rem 1.1rem; color: var(--fg-muted); }
.edr-body code { font-family: var(--mono); font-size: 0.875em; background: var(--bg-muted); padding: 0.1em 0.4em; border-radius: 4px; color: var(--fg); }
.edr-body pre {
  background: var(--bg-subtle); border: 1px solid var(--border-light); padding: 1rem 1.1rem;
  border-radius: 8px; overflow-x: auto; font-size: 0.86rem; line-height: 1.55; margin: 1rem 0;
}
.edr-body pre code { background: none; padding: 0; font-size: inherit; }
.edr-body table { border-collapse: collapse; margin: 1.25rem 0; font-size: 0.92rem; width: 100%; }
.edr-body th {
  text-align: left; padding: 0.55rem 0.9rem; font-family: var(--mono); font-size: 0.72rem;
  font-weight: 600; text-transform: uppercase; letter-spacing: 0.05em; color: var(--fg-muted);
  background: var(--bg-subtle); border-bottom: 1px solid var(--border-light);
}
.edr-body td { padding: 0.6rem 0.9rem; border-bottom: 1px solid var(--border-light); vertical-align: top; }
.edr-body tr:last-child td { border-bottom: 0; }
.edr-body hr { border: 0; border-top: 1px solid var(--border-light); margin: 2.5rem 0; }
.edr-body img { max-width: 100%; }

/* Inline SVG diagrams (replacing ASCII drawings) */
.edr-body svg.diagram {
  display: block;
  width: 100%;
  height: auto;
  max-width: 760px;
  margin: 1.5rem auto;
}
.edr-body svg.diagram text { font-family: var(--mono); }
.edr-body figure.diagram { margin: 1.5rem 0; }
.edr-body figure.diagram figcaption { font-size: 0.82rem; color: var(--fg-muted); text-align: center; margin-top: 0.4rem; font-family: var(--mono); }

.edr-footer {
  margin-top: 3.5rem; padding-top: 1.25rem; border-top: 1px solid var(--border-light);
  font-family: var(--mono); font-size: 0.78rem; color: var(--fg-muted);
}
.edr-footer a { color: var(--fg-secondary); text-decoration: none; }
.edr-footer a:hover { color: var(--accent); }
.edr-footer code { font-size: inherit; background: none; padding: 0; }

/* TOC */
.edr-toc { display: none; }
@media (min-width: 1140px) {
  .edr-toc { display: block; position: sticky; top: 4.5rem; align-self: start; font-size: 0.85rem; max-height: calc(100vh - 5.5rem); overflow-y: auto; }
}
.edr-toc-label {
  font-family: var(--mono); font-size: 0.7rem; font-weight: 600; text-transform: uppercase;
  letter-spacing: 0.06em; color: var(--fg-faint); margin: 0 0 0.75rem; padding-bottom: 0.5rem;
  border-bottom: 1px solid var(--border-light);
}
.edr-toc ul { list-style: none; margin: 0; padding: 0; }
.edr-toc li { margin: 0.4rem 0; line-height: 1.4; }
.edr-toc li.level-3 { padding-left: 1rem; font-size: 0.8rem; }
.edr-toc li.level-4 { padding-left: 2rem; font-size: 0.78rem; }
.edr-toc a { color: var(--fg-secondary); text-decoration: none; display: block; padding: 0.05rem 0; }
.edr-toc a:hover { color: var(--accent); }

/* Index / listing */
.intro { padding: 3rem 0 1.5rem; max-width: 44rem; }
.intro h1 { font-family: var(--display); font-size: 2rem; font-weight: 600; letter-spacing: -0.02em; line-height: 1.2; margin: 0 0 1rem; color: var(--fg); }
.intro p { font-size: 1.025rem; line-height: 1.65; color: var(--fg-secondary); margin: 0.75rem 0; }
.edr-list {
  margin: 1.5rem 0 4rem; border: 1px solid var(--border-light); border-radius: 10px;
  background: var(--bg); overflow: hidden; box-shadow: var(--shadow-sm);
}
.edr-list table { width: 100%; border-collapse: collapse; font-size: 0.95rem; }
.edr-list thead { background: var(--bg-subtle); border-bottom: 1px solid var(--border-light); }
.edr-list th {
  text-align: left; padding: 0.85rem 1rem; font-family: var(--mono); font-size: 0.7rem;
  font-weight: 600; text-transform: uppercase; letter-spacing: 0.06em; color: var(--fg-muted);
}
.edr-list td { padding: 0.85rem 1rem; border-bottom: 1px solid var(--border-light); vertical-align: top; }
.edr-list tr:last-child td { border-bottom: 0; }
.edr-list tr:hover td { background: var(--bg-subtle); }
.edr-list td.num { font-family: var(--mono); font-size: 0.85rem; color: var(--fg-muted); width: 4.5rem; white-space: nowrap; }
.edr-list td.num a { color: var(--fg-secondary); text-decoration: none; }
.edr-list td.date { font-family: var(--mono); font-size: 0.85rem; color: var(--fg-muted); white-space: nowrap; }
.edr-list td a { color: var(--fg); text-decoration: none; font-weight: 500; }
.edr-list td a:hover { color: var(--accent); text-decoration: underline; }

/* Status badges */
.badge {
  display: inline-block; padding: 0.18rem 0.6rem; border-radius: 999px; font-family: var(--mono);
  font-size: 0.72rem; font-weight: 600; text-transform: lowercase; letter-spacing: 0.03em; vertical-align: middle;
}
.badge-proposed   { background: hsl(35, 90%, 92%);  color: hsl(28, 60%, 32%);  }
.badge-accepted   { background: hsl(145, 50%, 90%); color: hsl(150, 45%, 25%); }
.badge-deprecated { background: hsl(20, 8%, 90%);   color: hsl(20, 8%, 35%);   }
.badge-superseded { background: hsl(270, 45%, 92%); color: hsl(265, 40%, 35%); }
@media (prefers-color-scheme: dark) {
  .badge-proposed   { background: hsl(35, 50%, 22%);  color: hsl(38, 85%, 80%); }
  .badge-accepted   { background: hsl(145, 35%, 18%); color: hsl(140, 60%, 78%); }
  .badge-deprecated { background: hsl(20, 8%, 22%);   color: hsl(30, 10%, 80%); }
  .badge-superseded { background: hsl(265, 30%, 22%); color: hsl(270, 60%, 85%); }
}
.tag {
  display: inline-block; padding: 0.12rem 0.5rem; border-radius: 4px; background: var(--bg-muted);
  font-family: var(--mono); font-size: 0.72rem; color: var(--fg-muted); margin-right: 0.3rem; vertical-align: middle;
}

/* embedded interactive diagrams */
iframe.embed {
  width: 100%; height: 560px; border: 1px solid var(--border-light); border-radius: 12px;
  background: var(--bg); margin: 1.5rem 0; box-shadow: var(--shadow-sm);
}
iframe.embed.tall { height: 700px; }

/* ---- Landing ---- */
.hero { padding: 3.5rem 0 2.5rem; max-width: 50rem; }
.hero-kicker { font-family: var(--mono); font-size: 0.78rem; letter-spacing: 0.08em; text-transform: uppercase; color: var(--accent); margin: 0 0 0.75rem; }
.hero h1 { font-family: var(--display); font-size: 4.5rem; font-weight: 600; letter-spacing: -0.03em; line-height: 0.95; margin: 0; color: var(--fg); }
@media (max-width: 600px) { .hero h1 { font-size: 3rem; } }
.hero-tag { font-family: var(--display); font-size: 1.5rem; color: var(--fg-secondary); margin: 0.6rem 0 1.25rem; font-style: italic; }
.hero-lede { font-size: 1.1rem; line-height: 1.7; color: var(--fg-secondary); margin: 0 0 1.75rem; }
.hero-lede b { color: var(--fg); font-weight: 600; }
.hero-cta { display: flex; flex-wrap: wrap; gap: 0.75rem; margin: 0 0 1.5rem; }
.btn-primary, .btn-ghost { display: inline-block; font-family: var(--mono); font-size: 0.85rem; font-weight: 600; padding: 0.6rem 1.1rem; border-radius: 9px; text-decoration: none; transition: all 0.12s ease; }
.btn-primary { background: var(--accent); color: #fff; border: 1px solid transparent; }
.btn-primary:hover { filter: brightness(1.07); }
.btn-ghost { background: var(--bg-subtle); color: var(--fg); border: 1px solid var(--border); }
.btn-ghost:hover { border-color: var(--fg-faint); }
.hero-status { font-family: var(--mono); font-size: 0.8rem; color: var(--fg-muted); border-left: 3px solid var(--accent); padding-left: 0.8rem; margin: 0; }
.hero-status b { color: var(--fg); }

.band, .explainer, .explore { padding: 2.5rem 0; border-top: 1px solid var(--border-light); }
.band h2, .explainer h2, .explore h2 { font-family: var(--display); font-size: 1.75rem; font-weight: 600; letter-spacing: -0.015em; margin: 0 0 1.25rem; color: var(--fg); }
.explainer p { font-size: 1.05rem; line-height: 1.75; color: var(--fg-secondary); max-width: 50rem; margin: 0 0 1rem; }
.explainer p b { color: var(--fg); }
.band-note { font-size: 1.02rem; line-height: 1.7; color: var(--fg-secondary); max-width: 50rem; margin: 1rem 0; }

.flow-strip { display: flex; flex-wrap: wrap; align-items: center; gap: 0.5rem; margin: 0.5rem 0; }
.flow-step { font-family: var(--mono); font-size: 0.82rem; color: var(--fg); background: var(--bg-subtle); border: 1px solid var(--border); border-radius: 8px; padding: 0.45rem 0.75rem; white-space: nowrap; }
.flow-step b { color: var(--accent); margin-right: 0.3rem; }
.flow-step.muted { color: var(--fg-muted); border-style: dashed; }
.flow-strip i { color: var(--fg-faint); font-style: normal; }

.feature-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(250px, 1fr)); gap: 1rem; }
.feature { background: var(--bg); border: 1px solid var(--border); border-radius: 12px; padding: 1.2rem 1.25rem; box-shadow: var(--shadow-sm); }
.feature h3 { font-family: var(--sans); font-size: 1.05rem; font-weight: 600; margin: 0 0 0.5rem; color: var(--fg); }
.feature p { font-size: 0.92rem; line-height: 1.6; color: var(--fg-secondary); margin: 0 0 0.75rem; }
.feature a { font-family: var(--mono); font-size: 0.75rem; color: var(--accent); text-decoration: none; }
.feature a:hover { text-decoration: underline; }

.card-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: 0.9rem; }
.card { display: flex; flex-direction: column; gap: 0.3rem; text-decoration: none; background: var(--bg-subtle); border: 1px solid var(--border-light); border-radius: 10px; padding: 1rem 1.1rem; transition: border-color 0.12s ease, transform 0.05s ease; }
.card:hover { border-color: var(--accent); transform: translateY(-1px); }
.card-t { font-weight: 600; color: var(--fg); }
.card-d { font-size: 0.88rem; color: var(--fg-secondary); }