/* Backchannel landing/site stylesheet. Self-contained: system fonts, no CDNs. */

:root {
  --ink: #0f172a;
  --ink-soft: #334155;
  --muted: #64748b;
  --paper: #f8fafc;
  --surface: #ffffff;
  --border: #e2e8f0;
  --accent: #0d9488;
  --accent-strong: #0f766e;
  --accent-soft: #ccfbf1;
  --code-bg: #0f172a;
  --code-ink: #e2e8f0;
  --shadow: 0 1px 2px rgba(15, 23, 42, 0.06), 0 8px 24px rgba(15, 23, 42, 0.06);
}

@media (prefers-color-scheme: dark) {
  :root {
    --ink: #e2e8f0;
    --ink-soft: #cbd5e1;
    --muted: #94a3b8;
    --paper: #0b1120;
    --surface: #101a30;
    --border: #1e293b;
    --accent: #2dd4bf;
    --accent-strong: #5eead4;
    --accent-soft: #113c37;
    --code-bg: #060b16;
    --code-ink: #cbd5e1;
    --shadow: 0 1px 2px rgba(0, 0, 0, 0.4), 0 8px 24px rgba(0, 0, 0, 0.35);
  }
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  font-size: 17px;
  line-height: 1.6;
  color: var(--ink);
  background: var(--paper);
  -webkit-font-smoothing: antialiased;
}

code, pre {
  font-family: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, "Liberation Mono", monospace;
}

.wrap {
  max-width: 1080px;
  margin: 0 auto;
  padding: 0 24px;
}

a {
  color: var(--accent);
  text-decoration: none;
}

a:hover {
  color: var(--accent-strong);
  text-decoration: underline;
}

/* Header */

header.site {
  position: sticky;
  top: 0;
  z-index: 10;
  background: color-mix(in srgb, var(--paper) 88%, transparent);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--border);
}

header.site .wrap {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding-top: 14px;
  padding-bottom: 14px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 700;
  font-size: 19px;
  color: var(--ink);
  letter-spacing: -0.3px;
}

.brand:hover {
  text-decoration: none;
}

.brand img {
  height: 28px;
  width: auto;
  display: block;
}

nav.site-nav {
  display: flex;
  align-items: center;
  gap: 22px;
  font-size: 15px;
}

nav.site-nav a {
  color: var(--ink-soft);
}

nav.site-nav a:hover {
  color: var(--accent);
  text-decoration: none;
}

/* Hero */

.hero {
  padding: 88px 0 64px;
  text-align: center;
}

.hero h1 {
  margin: 0 auto 20px;
  max-width: 820px;
  font-size: clamp(34px, 5.5vw, 56px);
  line-height: 1.12;
  letter-spacing: -1.5px;
}

.hero h1 .accent {
  color: var(--accent);
}

.hero p.lede {
  margin: 0 auto 36px;
  max-width: 680px;
  font-size: 19px;
  color: var(--muted);
}

.cta-row {
  display: flex;
  justify-content: center;
  gap: 14px;
  flex-wrap: wrap;
}

.btn {
  display: inline-block;
  padding: 12px 26px;
  border-radius: 10px;
  font-weight: 600;
  font-size: 16px;
  border: 1px solid transparent;
}

.btn:hover {
  text-decoration: none;
}

.btn.primary {
  background: var(--accent);
  color: #ffffff;
}

@media (prefers-color-scheme: dark) {
  .btn.primary {
    color: #04211d;
  }
}

.btn.primary:hover {
  background: var(--accent-strong);
}

.btn.ghost {
  border-color: var(--border);
  color: var(--ink);
  background: var(--surface);
}

.btn.ghost:hover {
  border-color: var(--accent);
  color: var(--accent);
}

/* Sections */

section {
  padding: 64px 0;
}

section.alt {
  background: var(--surface);
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
}

.kicker {
  display: block;
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 1.5px;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 8px;
}

section h2 {
  margin: 0 0 12px;
  font-size: 32px;
  letter-spacing: -0.8px;
}

section p.sub {
  margin: 0 0 40px;
  max-width: 640px;
  color: var(--muted);
}

section.cta-final {
  text-align: center;
}

section.cta-final p.sub {
  margin-left: auto;
  margin-right: auto;
}

/* Feature grid */

.grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}

.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 24px;
  box-shadow: var(--shadow);
}

section.alt .card {
  background: var(--paper);
}

.card h3 {
  margin: 0 0 8px;
  font-size: 18px;
  letter-spacing: -0.3px;
}

.card p {
  margin: 0;
  font-size: 15px;
  color: var(--muted);
}

.card .icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  border-radius: 10px;
  background: var(--accent-soft);
  color: var(--accent);
  font-size: 20px;
  margin-bottom: 14px;
}

/* Steps */

ol.steps {
  list-style: none;
  counter-reset: step;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 14px;
}

ol.steps li {
  counter-increment: step;
  display: flex;
  gap: 16px;
  align-items: baseline;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 16px 20px;
}

section.alt ol.steps li {
  background: var(--paper);
}

ol.steps li::before {
  content: counter(step);
  flex: 0 0 auto;
  width: 30px;
  height: 30px;
  border-radius: 50%;
  background: var(--accent);
  color: #ffffff;
  font-weight: 700;
  font-size: 15px;
  display: flex;
  align-items: center;
  justify-content: center;
  align-self: center;
}

@media (prefers-color-scheme: dark) {
  ol.steps li::before {
    color: #04211d;
  }
}

ol.steps li strong {
  color: var(--ink);
}

ol.steps li span {
  color: var(--muted);
  font-size: 15.5px;
}

/* Architecture */

.diagram {
  background: #fcfcfd;
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 12px;
  overflow-x: auto;
  box-shadow: var(--shadow);
}

.diagram img {
  display: block;
  min-width: 720px;
  width: 100%;
  height: auto;
}

/* Tables */

.table-scroll {
  overflow-x: auto;
  border: 1px solid var(--border);
  border-radius: 12px;
  background: var(--surface);
}

table {
  width: 100%;
  border-collapse: collapse;
  font-size: 15px;
}

th, td {
  text-align: left;
  padding: 12px 16px;
  border-bottom: 1px solid var(--border);
  vertical-align: top;
}

tr:last-child td {
  border-bottom: none;
}

th {
  font-size: 13px;
  text-transform: uppercase;
  letter-spacing: 0.8px;
  color: var(--muted);
}

td code {
  background: var(--accent-soft);
  color: var(--accent-strong);
  padding: 1px 6px;
  border-radius: 6px;
  font-size: 13.5px;
}

/* Code blocks */

pre {
  background: var(--code-bg);
  color: var(--code-ink);
  border-radius: 12px;
  padding: 20px 24px;
  overflow-x: auto;
  font-size: 14.5px;
  line-height: 1.7;
  margin: 0;
}

pre .cmt {
  color: #64748b;
}

.quickstart-note {
  margin-top: 14px;
  font-size: 15px;
  color: var(--muted);
}

/* Docs list */

.doc-list {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 14px;
}

.doc-list a.doc {
  display: block;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 16px 20px;
  color: var(--ink);
}

.doc-list a.doc:hover {
  text-decoration: none;
  border-color: var(--accent);
}

.doc-list a.doc strong {
  display: block;
  margin-bottom: 2px;
}

.doc-list a.doc span {
  font-size: 14.5px;
  color: var(--muted);
}

/* Comparison-page prose */

.prose {
  max-width: 760px;
}

.prose h3 {
  margin: 28px 0 8px;
  font-size: 20px;
  letter-spacing: -0.3px;
}

.prose p {
  margin: 0 0 14px;
  color: var(--ink-soft);
}

/* Footer */

footer.site {
  border-top: 1px solid var(--border);
  padding: 32px 0 48px;
  font-size: 14.5px;
  color: var(--muted);
}

footer.site .wrap {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  flex-wrap: wrap;
}

footer.site .wrap.footer-compare {
  justify-content: flex-start;
  gap: 8px 20px;
  padding-bottom: 14px;
  margin-bottom: 14px;
  border-bottom: 1px solid var(--border);
}

/* Responsive */

@media (max-width: 900px) {
  .grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 720px) {
  body {
    font-size: 16px;
  }

  nav.site-nav {
    display: none;
  }

  .hero {
    padding: 56px 0 40px;
  }

  section {
    padding: 44px 0;
  }

  .grid,
  .doc-list {
    grid-template-columns: 1fr;
  }
}