/* substrate — schematic / operator-console design language */

:root {
  --bg: #FFFFFF;
  --surface: #FAFAFA;
  --surface-2: #F4F4F5;
  --line: #E4E4E7;
  --line-strong: #D4D4D8;
  --ink: #0A0A0A;
  --ink-2: #18181B;
  --muted: #52525B;
  --faint: #71717A;
  --accent: #1E40AF;
  --accent-strong: #1E3A8A;
  --accent-bg: #EFF6FF;
  --ok: #15803D;
  --warn: #B45309;
  --grid: rgba(228, 228, 231, 0.4);

  --sans: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  --mono: 'JetBrains Mono', ui-monospace, 'SF Mono', Menlo, monospace;

  --r-1: 4px;
  --r-2: 6px;
  --r-3: 10px;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0A0E14;
    --surface: #11161F;
    --surface-2: #1A2030;
    --line: #1E2533;
    --line-strong: #2A3144;
    --ink: #F4F4F5;
    --ink-2: #E4E4E7;
    --muted: #9CA3AF;
    --faint: #6B7280;
    --accent: #60A5FA;
    --accent-strong: #93C5FD;
    --accent-bg: rgba(96, 165, 250, 0.10);
    --ok: #34D399;
    --warn: #FBBF24;
    --grid: rgba(30, 37, 51, 0.6);
  }
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; }
body {
  background: var(--bg);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 15px;
  line-height: 1.55;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  font-feature-settings: 'cv11', 'ss01', 'ss03', 'tnum';
  min-height: 100vh;
  position: relative;
  background-image:
    linear-gradient(to right, var(--grid) 1px, transparent 1px),
    linear-gradient(to bottom, var(--grid) 1px, transparent 1px);
  background-size: 80px 80px;
  background-position: -1px -1px;
}

a { color: inherit; text-decoration: none; }
::selection { background: var(--accent); color: #FFF; }

a.skip {
  position: fixed; top: -40px; left: 8px;
  background: var(--ink); color: var(--bg);
  padding: 6px 10px; border-radius: var(--r-1);
  font-family: var(--mono); font-size: 12px; letter-spacing: .04em;
  z-index: 100;
  transition: top .15s ease;
}
a.skip:focus-visible { top: 8px; outline: 2px solid var(--accent); outline-offset: 2px; }

/* ---------- header ---------- */
header {
  position: sticky; top: 0; z-index: 50;
  display: flex; align-items: center; justify-content: space-between;
  padding: 12px 24px;
  background: color-mix(in oklab, var(--bg) 88%, transparent);
  backdrop-filter: blur(10px) saturate(140%);
  -webkit-backdrop-filter: blur(10px) saturate(140%);
  border-bottom: 1px solid var(--line);
}
.hd-l { display: flex; align-items: center; gap: 16px; }
.logo {
  display: inline-flex; align-items: center; gap: 8px;
  font-family: var(--sans); font-size: 15px; font-weight: 600; letter-spacing: -.012em;
}
.logo-mark {
  width: 12px; height: 12px;
  border: 1.5px solid var(--accent);
  background: linear-gradient(135deg, var(--accent) 0 50%, transparent 50% 100%);
}
.logo-mark.small { width: 10px; height: 10px; }
.meta-pill {
  display: inline-flex; align-items: center; gap: 6px;
  padding: 4px 10px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: var(--surface);
  font-family: var(--mono); font-size: 11px;
}
.meta-pill .dot { width: 3px; height: 3px; background: var(--line-strong); border-radius: 50%; }
.meta-pill .meta-k { color: var(--faint); }
.meta-pill .meta-v { color: var(--ink-2); font-weight: 500; }
.meta-pill .meta-v.ok { color: var(--ok); }
.meta-pill .meta-v.ok::before { content: "● "; }

@media (max-width: 760px) { .meta-pill { display: none; } }

.hd-r { display: flex; align-items: center; gap: 4px; }
.hd-r a {
  padding: 6px 12px;
  font-size: 13px; font-weight: 500;
  color: var(--muted);
  border-radius: var(--r-2);
  transition: color .15s, background .15s;
}
.hd-r a:hover { color: var(--ink); background: var(--surface); }
.hd-r a.primary {
  color: var(--ink); background: var(--surface);
  border: 1px solid var(--line-strong);
}
.hd-r a.primary:hover { background: var(--surface-2); }
@media (max-width: 760px) {
  .hd-r a:not(.primary) { display: none; }
}

/* ---------- main / frame system ---------- */
main {
  max-width: 1080px; margin: 0 auto;
  padding: 32px 24px 80px;
}

.frame {
  display: grid;
  grid-template-columns: 88px 1fr;
  gap: 0;
  border: 1px solid var(--line);
  background: var(--bg);
  margin-bottom: 24px;
  position: relative;
}
.frame::before {
  content: ""; position: absolute; left: -3px; top: -3px;
  width: 6px; height: 6px;
  border-left: 2px solid var(--accent); border-top: 2px solid var(--accent);
}
.frame::after {
  content: ""; position: absolute; right: -3px; bottom: -3px;
  width: 6px; height: 6px;
  border-right: 2px solid var(--accent); border-bottom: 2px solid var(--accent);
}
.frame-rule {
  display: flex; flex-direction: column; align-items: flex-end;
  padding: 16px 12px;
  border-right: 1px solid var(--line);
  background: var(--surface);
  font-family: var(--mono);
}
.frame-rule span:first-child {
  font-size: 22px; font-weight: 600; color: var(--ink);
  font-feature-settings: 'tnum';
  letter-spacing: -.02em;
  line-height: 1;
}
.frame-rule span:last-child {
  font-size: 10px; text-transform: uppercase; letter-spacing: .14em; color: var(--faint);
  margin-top: 4px;
}
.frame-body { padding: 24px 28px 28px; }

@media (max-width: 640px) {
  .frame { grid-template-columns: 56px 1fr; }
  .frame-rule { padding: 12px 8px; }
  .frame-rule span:first-child { font-size: 18px; }
  .frame-body { padding: 16px 18px 20px; }
}

/* ---------- hero ---------- */
.hero { margin-top: 16px; margin-bottom: 24px; }
.hero .frame { background: var(--bg); }
.hero .frame-rule { background: var(--accent-bg); }
.hero .frame-rule span:first-child { color: var(--accent); }
.kicker {
  font-family: var(--mono); font-size: 11px; font-weight: 500;
  text-transform: uppercase; letter-spacing: .16em;
  color: var(--accent); margin-bottom: 14px;
}
.hero h1 {
  font-family: var(--sans); font-weight: 700;
  font-size: clamp(28px, 4.6vw, 52px);
  line-height: 1.05; letter-spacing: -.025em;
  color: var(--ink); margin-bottom: 18px;
  text-wrap: balance;
}
.hero h1 .accent { color: var(--accent); }
.lede {
  font-size: 17px; line-height: 1.55; color: var(--ink-2);
  max-width: 60ch; margin-bottom: 20px;
}
.lede em { font-style: italic; color: var(--ink); }
.lede strong { font-weight: 600; color: var(--ink); }
.cta-row { display: flex; gap: 8px; flex-wrap: wrap; margin-top: 24px; }
.btn-primary, .btn-ghost {
  display: inline-flex; align-items: center; gap: 6px;
  padding: 9px 16px; min-height: 36px;
  font-family: var(--sans); font-size: 13px; font-weight: 500;
  border-radius: var(--r-2);
  transition: background .15s, color .15s, border-color .15s, transform .12s;
  cursor: pointer;
}
.btn-primary {
  background: var(--ink); color: var(--bg);
  border: 1px solid var(--ink);
}
.btn-primary:hover { background: var(--ink-2); transform: translateY(-1px); }
.btn-ghost {
  background: transparent; color: var(--ink-2);
  border: 1px solid var(--line-strong);
}
.btn-ghost:hover { border-color: var(--ink); background: var(--surface); }

/* ---------- block / typography ---------- */
.block { margin-bottom: 24px; }
.block h2 {
  font-family: var(--sans); font-weight: 600;
  font-size: 19px; letter-spacing: -.012em;
  color: var(--ink); margin: 0 0 12px;
}
.block h2:not(:first-child) { margin-top: 28px; }
.block p {
  font-size: 15px; line-height: 1.6; color: var(--ink-2);
  max-width: 70ch; margin-bottom: 12px;
}
.block p em { color: var(--accent); font-style: italic; font-weight: 500; }
.block p strong { color: var(--ink); font-weight: 600; }
.block code {
  font-family: var(--mono); font-size: 12.5px;
  background: var(--surface-2);
  padding: 2px 6px; border-radius: var(--r-1);
  color: var(--ink-2);
  border: 1px solid var(--line);
}
pre {
  font-family: var(--mono); font-size: 13px; line-height: 1.55;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--r-2);
  padding: 14px 16px;
  overflow-x: auto;
  margin: 14px 0;
  color: var(--ink-2);
}
pre code { background: transparent; padding: 0; border: 0; font-size: 13px; }

/* ---------- objects (cards) ---------- */
.objects {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 12px;
  margin-top: 16px;
}
.obj {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--r-2);
  padding: 14px 16px;
  position: relative;
}
.obj-label {
  font-family: var(--mono); font-size: 10px;
  text-transform: uppercase; letter-spacing: .12em;
  color: var(--faint);
  margin-bottom: 4px;
}
.obj h3 {
  font-family: var(--sans); font-weight: 600;
  font-size: 16px; letter-spacing: -.005em;
  color: var(--ink); margin-bottom: 8px;
}
.obj p {
  font-size: 13.5px; line-height: 1.5;
  color: var(--ink-2); margin: 0;
}
.obj code { font-size: 11.5px; }

/* ---------- tables ---------- */
table.who, table.layers {
  width: 100%; border-collapse: collapse;
  margin-top: 8px;
  font-family: var(--sans); font-size: 14px;
}
table.who thead th, table.layers thead th {
  font-family: var(--mono); font-size: 11px; font-weight: 500;
  text-transform: uppercase; letter-spacing: .1em;
  color: var(--faint);
  text-align: left;
  padding: 8px 12px 10px;
  border-bottom: 1px solid var(--line);
}
table.who tbody td, table.layers tbody td {
  padding: 11px 12px;
  border-bottom: 1px solid var(--line);
  vertical-align: top;
}
table.who tbody tr:last-child td, table.layers tbody tr:last-child td {
  border-bottom: none;
}
table.who tbody tr:hover, table.layers tbody tr:hover {
  background: var(--surface);
}
table.who tbody td:first-child {
  width: 160px; padding-right: 8px;
}
table.who tbody td:last-child { color: var(--ink-2); }

.tag {
  display: inline-flex; align-items: center;
  padding: 3px 8px;
  font-family: var(--mono); font-size: 11px; font-weight: 500;
  background: var(--surface-2);
  border: 1px solid var(--line);
  border-radius: var(--r-1);
  color: var(--ink-2);
  letter-spacing: .02em;
}

table.layers tbody td:nth-child(1) {
  width: 36px; font-family: var(--mono); font-size: 12px;
  color: var(--faint); font-feature-settings: 'tnum';
}
table.layers tbody td:nth-child(2) {
  font-family: var(--mono); font-size: 12.5px; font-weight: 500;
  color: var(--ink);
  width: 130px;
}
table.layers tbody td:nth-child(3) {
  width: 30%;
}
table.layers tbody td:nth-child(3) code { font-size: 11.5px; }
table.layers tbody td:nth-child(4) { color: var(--ink-2); font-size: 13.5px; }

@media (max-width: 640px) {
  table.who tbody td:first-child { width: auto; }
  table.layers tbody td:nth-child(2) { width: auto; }
  table.layers tbody td:nth-child(3) { width: auto; }
  table.who, table.layers { font-size: 13px; }
}

.close p a {
  color: var(--accent);
  border-bottom: 1px solid var(--accent);
  padding-bottom: 1px;
  font-weight: 500;
  font-family: var(--mono);
  font-size: 14px;
}
.close p a:hover { background: var(--accent-bg); }

/* ---------- FAQ ---------- */
.qa {
  border-bottom: 1px solid var(--line);
  padding: 0;
}
.qa:last-of-type { border-bottom: none; }
.qa summary {
  list-style: none;
  cursor: pointer;
  padding: 14px 0;
  font-weight: 500;
  font-size: 15px;
  color: var(--ink);
  display: flex;
  align-items: flex-start;
  gap: 10px;
  position: relative;
  user-select: none;
}
.qa summary::-webkit-details-marker { display: none; }
.qa summary::before {
  content: "+";
  font-family: var(--mono);
  font-size: 14px;
  color: var(--accent);
  flex: none;
  width: 14px;
  line-height: 1.4;
  font-weight: 600;
  transition: transform .15s ease;
}
.qa[open] summary::before { content: "−"; }
.qa summary:hover { color: var(--accent); }
.qa[open] summary { color: var(--ink); }
.qa p {
  font-size: 14.5px; line-height: 1.6; color: var(--ink-2);
  padding: 0 0 16px 24px;
  margin: 0;
  max-width: 70ch;
}
.qa p a {
  color: var(--accent);
  border-bottom: 1px solid var(--accent);
  padding-bottom: 1px;
}
.qa p a:hover { background: var(--accent-bg); }

/* ---------- footer ---------- */
footer {
  border-top: 1px solid var(--line);
  margin-top: 24px;
  padding: 16px 24px;
  display: flex; align-items: center; justify-content: space-between;
  font-family: var(--mono); font-size: 12px;
  color: var(--muted);
  background: var(--surface);
}
.ftr-l, .ftr-r {
  display: flex; align-items: center; gap: 10px;
}
.ftr-sep { color: var(--line-strong); }
footer a {
  color: var(--ink-2);
  border-bottom: 1px solid transparent;
  padding-bottom: 1px;
  transition: color .15s, border-color .15s;
}
footer a:hover { color: var(--accent); border-bottom-color: var(--accent); }
.mono { font-family: var(--mono); }
@media (max-width: 480px) {
  footer { flex-direction: column; gap: 10px; align-items: flex-start; }
}

/* ---------- focus ---------- */
:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
  border-radius: var(--r-1);
}

/* ---------- reduced motion ---------- */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { transition-duration: .01ms !important; animation-duration: .01ms !important; }
}