:root {
  --bg: #0c1929;
  --bg-2: #0f1e33;
  --bg-elevated: rgba(255, 255, 255, 0.03);
  --ink: #e2e8f0;
  --ink-soft: #94a3b8;
  --ink-muted: #64748b;
  --accent: #0ea5e9;
  --accent-soft: #38bdf8;
  --accent-bg: rgba(14, 165, 233, 0.08);
  --rule: rgba(148, 163, 184, 0.18);
  --rule-strong: rgba(148, 163, 184, 0.35);
  --max-width: 1120px;
  --font-sans: -apple-system, BlinkMacSystemFont, "SF Pro Display", "SF Pro Text",
    "Helvetica Neue", Helvetica, Arial, system-ui, sans-serif;
  --font-mono: ui-monospace, "SF Mono", "JetBrains Mono", Menlo, Consolas,
    "DejaVu Sans Mono", monospace;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  background-image:
    linear-gradient(rgba(148, 163, 184, 0.06) 1px, transparent 1px),
    linear-gradient(90deg, rgba(148, 163, 184, 0.06) 1px, transparent 1px),
    radial-gradient(1200px 800px at 80% -10%, rgba(14, 165, 233, 0.10), transparent 60%);
  background-size: 32px 32px, 32px 32px, auto;
  background-attachment: fixed, fixed, fixed;
  color: var(--ink);
  font-family: var(--font-sans);
  font-size: 17px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
}

a { color: var(--accent-soft); text-decoration: none; transition: opacity 0.15s ease; }
a:hover { opacity: 0.75; }

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 28px;
}

/* ---------- Header ---------- */

.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  background: rgba(12, 25, 41, 0.82);
  backdrop-filter: saturate(180%) blur(18px);
  -webkit-backdrop-filter: saturate(180%) blur(18px);
  border-bottom: 1px solid var(--rule);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  color: var(--ink);
  font-weight: 600;
}

.brand-mark {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 30px;
  height: 30px;
  border-radius: 6px;
  background: var(--accent);
  color: var(--bg);
  font-weight: 700;
  font-size: 16px;
  font-family: var(--font-mono);
}
.brand-mark.small { width: 22px; height: 22px; font-size: 13px; border-radius: 4px; }

.brand-name { letter-spacing: -0.01em; }

.site-nav { display: flex; gap: 28px; font-size: 14px; color: var(--ink-soft); font-family: var(--font-mono); }
.site-nav a { color: var(--ink-soft); }
.site-nav a:hover { color: var(--accent-soft); opacity: 1; }

/* ---------- Hero ---------- */

.hero { padding: 100px 0 80px; }

.hero-grid {
  display: grid;
  grid-template-columns: 1.2fr 1fr;
  gap: 56px;
  align-items: center;
}

.meta-tag {
  font-family: var(--font-mono);
  color: var(--accent-soft);
  font-size: 13px;
  letter-spacing: 0.04em;
  margin-bottom: 24px;
  display: inline-block;
}

.hero h1 {
  font-size: clamp(40px, 5vw, 60px);
  line-height: 1.06;
  letter-spacing: -0.022em;
  font-weight: 700;
  margin: 0 0 24px;
  color: var(--ink);
}

.hero-accent {
  background: linear-gradient(120deg, #67e8f9 0%, #38bdf8 50%, #818cf8 100%);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
  white-space: nowrap;
}

.hero .lede {
  font-size: 19px;
  line-height: 1.55;
  color: var(--ink-soft);
  max-width: 58ch;
  margin: 0 0 32px;
}

.spec-strip {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
  margin: 0;
  border-top: 1px solid var(--rule);
  border-bottom: 1px solid var(--rule);
  padding: 16px 0;
}

.spec-strip > div { padding: 0; }

.spec-strip dt {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--ink-muted);
  margin-bottom: 4px;
}

.spec-strip dd {
  margin: 0;
  font-family: var(--font-mono);
  font-size: 13px;
  color: var(--ink);
}

.hero-art svg {
  width: 100%;
  height: auto;
  border-radius: 12px;
  background: rgba(0, 0, 0, 0.25);
  border: 1px solid var(--rule);
}

/* ---------- Sections ---------- */

section { padding: 96px 0; border-top: 1px solid var(--rule); }

.section-head {
  margin-bottom: 56px;
  display: flex;
  align-items: baseline;
  gap: 16px;
}

.section-num {
  font-family: var(--font-mono);
  color: var(--accent-soft);
  font-size: 14px;
  letter-spacing: 0.06em;
}

section h2 {
  font-size: clamp(28px, 3.5vw, 38px);
  letter-spacing: -0.015em;
  font-weight: 700;
  margin: 0;
  color: var(--ink);
}

/* ---------- Spec cards ---------- */

.spec-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1px;
  background: var(--rule);
  border: 1px solid var(--rule);
  border-radius: 12px;
  overflow: hidden;
}

.spec {
  position: relative;
  background: var(--bg);
  padding: 32px;
}

.spec-rule {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 2px;
  background: linear-gradient(90deg, var(--accent), transparent);
  opacity: 0.55;
}

.spec-head {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.08em;
  margin-bottom: 20px;
}

.spec-id {
  color: var(--accent-soft);
  font-weight: 600;
}

.spec-status {
  color: var(--ink-muted);
  padding: 3px 8px;
  border: 1px solid var(--rule);
  border-radius: 4px;
}

.spec h3 {
  font-size: 20px;
  font-weight: 600;
  letter-spacing: -0.01em;
  margin: 0 0 12px;
  color: var(--ink);
}

.spec p {
  margin: 0 0 18px;
  color: var(--ink-soft);
  font-size: 15px;
  line-height: 1.55;
}

.spec-list {
  list-style: none;
  margin: 0;
  padding: 14px 0 0;
  border-top: 1px solid var(--rule);
}

.spec-list li {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--ink-soft);
  padding: 4px 0;
  position: relative;
  padding-left: 16px;
}

.spec-list li::before {
  content: "›";
  position: absolute;
  left: 0;
  color: var(--accent-soft);
}

/* ---------- Approach / protocol list ---------- */

.protocol {
  list-style: none;
  counter-reset: step;
  padding: 0;
  margin: 0;
  border-left: 1px solid var(--rule);
}

.protocol li {
  display: grid;
  grid-template-columns: 80px 1fr;
  gap: 32px;
  padding: 28px 0;
  border-bottom: 1px solid var(--rule);
}
.protocol li:last-child { border-bottom: none; }

.step-marker {
  font-family: var(--font-mono);
  font-size: 14px;
  color: var(--accent-soft);
  background: var(--accent-bg);
  border: 1px solid var(--accent);
  border-radius: 6px;
  padding: 8px 10px;
  height: max-content;
  width: max-content;
  margin-left: -1px;
}

.protocol h3 {
  margin: 0 0 8px;
  font-size: 22px;
  font-weight: 600;
  color: var(--ink);
  letter-spacing: -0.01em;
}

.protocol p {
  margin: 0;
  color: var(--ink-soft);
  font-size: 16px;
}

/* ---------- Policy pages ---------- */

.policy { padding: 80px 0 96px; }

.policy .container { max-width: 740px; }

.policy h1 {
  font-size: clamp(32px, 4.5vw, 44px);
  letter-spacing: -0.02em;
  font-weight: 700;
  margin: 0 0 8px;
  color: var(--ink);
}

.policy .updated {
  font-family: var(--font-mono);
  color: var(--accent-soft);
  font-size: 13px;
  letter-spacing: 0.04em;
  margin: 0 0 40px;
}

.policy h2 {
  font-size: 20px;
  font-weight: 600;
  margin: 40px 0 12px;
  letter-spacing: -0.005em;
  color: var(--ink);
}

.policy p, .policy li {
  color: var(--ink-soft);
  font-size: 16px;
  line-height: 1.65;
}

.policy ul {
  padding-left: 22px;
  margin: 0 0 16px;
}

.policy a {
  color: var(--accent-soft);
  text-decoration: underline;
  text-underline-offset: 3px;
  text-decoration-color: rgba(56, 189, 248, 0.35);
}

/* ---------- Footer ---------- */

.site-footer {
  border-top: 1px solid var(--rule);
  padding: 32px 0;
  font-size: 13px;
  color: var(--ink-muted);
  background: rgba(0, 0, 0, 0.25);
}

.footer-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  flex-wrap: wrap;
}

.footer-brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  color: var(--ink-soft);
}

.footer-meta {
  display: flex;
  align-items: center;
  gap: 18px;
  flex-wrap: wrap;
}

.footer-mono { font-family: var(--font-mono); font-size: 12px; }

.footer-links a { color: var(--ink-muted); }
.footer-links a:hover { color: var(--accent-soft); opacity: 1; }
.footer-links .dot { margin: 0 6px; color: var(--rule-strong); }

/* ---------- Responsive ---------- */

@media (max-width: 880px) {
  .hero-grid { grid-template-columns: 1fr; gap: 32px; }
  .hero-art { max-width: 460px; margin: 0 auto; }
}

@media (max-width: 760px) {
  .hero { padding: 70px 0 56px; }
  section { padding: 64px 0; }
  .spec-grid { grid-template-columns: 1fr; }
  .protocol li { grid-template-columns: 1fr; gap: 12px; }
  .site-nav { gap: 18px; font-size: 13px; }
  .footer-inner { justify-content: flex-start; }
}