:root {
  --bg: #ffffff;
  --bg-subtle: #fafafa;
  --border: #e5e5e5;
  --text: #171717;
  --text-muted: #6b6b6b;
  --accent: #171717;
  --done-bg: #f0f7f0;
  --done-border: #b7d9b7;
  --done-text: #2f6b2f;
  --planned-bg: #f5f5f5;
  --planned-border: #dcdcdc;
  --planned-text: #6b6b6b;
  --mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, monospace;
  --sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  --radius: 10px;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--sans);
  line-height: 1.55;
  -webkit-font-smoothing: antialiased;
}

a { color: inherit; }

/* Nav */
.nav {
  position: sticky;
  top: 0;
  z-index: 10;
  background: rgba(255, 255, 255, 0.85);
  backdrop-filter: saturate(180%) blur(6px);
  border-bottom: 1px solid var(--border);
}
.nav-inner {
  max-width: 880px;
  margin: 0 auto;
  padding: 14px 20px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 10px;
}
.nav-brand {
  font-weight: 600;
  font-size: 14px;
  font-family: var(--mono);
}
.nav-links {
  display: flex;
  gap: 18px;
  font-size: 13px;
}
.nav-links a {
  text-decoration: none;
  color: var(--text-muted);
  transition: color 0.15s ease;
}
.nav-links a:hover { color: var(--text); }

/* Hero */
.hero {
  max-width: 880px;
  margin: 0 auto;
  padding: 72px 20px 48px;
  text-align: left;
}
.status-pill {
  display: inline-block;
  font-family: var(--mono);
  font-size: 12px;
  color: var(--done-text);
  background: var(--done-bg);
  border: 1px solid var(--done-border);
  border-radius: 999px;
  padding: 4px 12px;
  margin-bottom: 20px;
}
.hero h1 {
  font-size: 40px;
  line-height: 1.15;
  margin: 0 0 14px;
  letter-spacing: -0.01em;
}
.subtitle {
  font-size: 17px;
  color: var(--text-muted);
  max-width: 560px;
  margin: 0 0 28px;
}
.cta {
  display: inline-block;
  text-decoration: none;
  font-size: 14px;
  font-weight: 600;
  color: #fff;
  background: var(--accent);
  padding: 11px 20px;
  border-radius: var(--radius);
  transition: opacity 0.15s ease;
}
.cta:hover { opacity: 0.85; }

/* Sections */
main {
  max-width: 880px;
  margin: 0 auto;
  padding: 0 20px;
}
.section {
  padding: 56px 0;
  border-top: 1px solid var(--border);
}
.section h2 {
  font-size: 22px;
  margin: 0 0 6px;
  letter-spacing: -0.01em;
}
.section-lede {
  color: var(--text-muted);
  font-size: 14px;
  margin: 0 0 32px;
}

/* Badges */
.badge {
  font-family: var(--mono);
  font-size: 11px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.03em;
  border-radius: 999px;
  padding: 3px 10px;
  white-space: nowrap;
}
.badge.done {
  color: var(--done-text);
  background: var(--done-bg);
  border: 1px solid var(--done-border);
}
.badge.planned {
  color: var(--planned-text);
  background: var(--planned-bg);
  border: 1px solid var(--planned-border);
}

/* Timeline / phases */
.timeline {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 16px;
}
.phase {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px 22px;
  background: var(--bg-subtle);
}
.phase-head {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 10px;
  flex-wrap: wrap;
}
.phase-num {
  font-family: var(--mono);
  font-size: 12px;
  color: var(--text-muted);
}
.phase-head h3 {
  font-size: 16px;
  margin: 0;
  flex: 1;
}
.phase-flow {
  font-family: var(--mono);
  font-size: 13px;
  color: var(--text);
  background: #fff;
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 8px 12px;
  display: inline-block;
  margin: 0 0 12px;
}
.phase-list {
  margin: 0;
  padding-left: 18px;
  font-size: 14px;
  color: var(--text);
  columns: 2;
  column-gap: 24px;
}
.phase-list li { margin-bottom: 4px; break-inside: avoid; }
.phase-note {
  margin: 12px 0 0;
  font-size: 13px;
  color: var(--text-muted);
  font-style: italic;
}

/* Stack */
.stack-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
  gap: 18px;
}
.stack-group h4 {
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--text-muted);
  margin: 0 0 8px;
}
.chips { display: flex; flex-wrap: wrap; gap: 6px; }
.chip {
  font-family: var(--mono);
  font-size: 12px;
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 4px 9px;
  background: #fff;
}

/* Architecture diagram */
.diagram {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 2px;
  margin-bottom: 32px;
}
.node {
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 10px 18px;
  font-size: 14px;
  font-family: var(--mono);
  background: var(--bg-subtle);
  min-width: 200px;
  text-align: center;
}
.arrow {
  color: var(--text-muted);
  font-size: 14px;
  line-height: 1;
}
.roles {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
  justify-content: center;
}
.role {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 12px 16px;
  font-size: 13px;
  display: flex;
  flex-direction: column;
  gap: 2px;
  min-width: 140px;
  text-align: center;
}
.role span { color: var(--text-muted); }

/* Verification compare */
.compare {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 18px;
}
.compare-single { grid-template-columns: 1fr; max-width: 380px; }
.compare-col {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 18px 20px;
}
.compare-col h4 {
  font-family: var(--mono);
  margin: 10px 0 8px;
  font-size: 15px;
}
.compare-col p {
  font-size: 13px;
  color: var(--text-muted);
  margin: 0;
}

/* Lifecycle */
.lifecycle {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 6px;
  font-size: 13px;
  font-family: var(--mono);
  margin-bottom: 28px;
}
.lifecycle span {
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 5px 10px;
  background: var(--bg-subtle);
}
.lifecycle .sep {
  border: none;
  background: none;
  color: var(--text-muted);
  padding: 0;
}
.lifecycle .done-step {
  background: var(--done-bg);
  border-color: var(--done-border);
  color: var(--done-text);
}
.planned-block { border-top: 1px dashed var(--border); padding-top: 20px; }
.planned-block .badge { margin-bottom: 10px; display: inline-block; }

/* Repo */
.repo-card {
  display: flex;
  align-items: center;
  gap: 12px;
  flex-wrap: wrap;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 14px 18px;
  background: var(--bg-subtle);
}
.repo-card code {
  font-family: var(--mono);
  font-size: 14px;
  background: #fff;
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 4px 10px;
}
.repo-note { font-size: 13px; color: var(--text-muted); }

main { padding-bottom: 48px; }

/* Mobile */
@media (max-width: 640px) {
  .hero { padding: 56px 20px 40px; }
  .hero h1 { font-size: 30px; }
  .nav-links { gap: 12px; font-size: 12px; }
  .phase-list { columns: 1; }
  .compare { grid-template-columns: 1fr; }
  .diagram .node { min-width: 0; width: 100%; }
}