/* MTPROTO — Measurement & Traceability Protocol
   Site styles. No external resources (fonts, images, scripts) are referenced. */

:root {
  --bg: #fbfbf9;
  --bg-alt: #f2f2ee;
  --panel: #ffffff;
  --ink: #1d2321;
  --ink-soft: #55605c;
  --ink-faint: #838e8a;
  --rule: #e0e2dd;
  --rule-strong: #cfd3cd;
  --accent: #14655e;
  --accent-soft: #e4efed;
  --code-bg: #f4f5f2;
  --warn: #8a5a12;
  --radius: 4px;
  --mono: ui-monospace, "SFMono-Regular", "SF Mono", Menlo, Consolas, "Liberation Mono", monospace;
  --sans: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #14171a;
    --bg-alt: #1a1e21;
    --panel: #1c2124;
    --ink: #e2e6e4;
    --ink-soft: #a6afab;
    --ink-faint: #7b8481;
    --rule: #2a3034;
    --rule-strong: #3a4247;
    --accent: #5cbdb0;
    --accent-soft: #1d2b2a;
    --code-bg: #171b1e;
    --warn: #d0a35a;
  }
}

* { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 16px;
  line-height: 1.62;
  -webkit-font-smoothing: antialiased;
}

.wrap {
  width: 100%;
  max-width: 960px;
  margin: 0 auto;
  padding: 0 24px;
}

a { color: var(--accent); text-decoration-thickness: 1px; text-underline-offset: 2px; }
a:hover { text-decoration-thickness: 2px; }

h1, h2, h3, h4 { line-height: 1.25; font-weight: 600; letter-spacing: -0.01em; }
h2 { font-size: 1.32rem; margin: 2.6rem 0 0.8rem; }
h3 { font-size: 1.05rem; margin: 1.9rem 0 0.5rem; }
p { margin: 0 0 1rem; }

code, kbd, samp, pre { font-family: var(--mono); font-size: 0.875em; }

:not(pre) > code {
  background: var(--code-bg);
  border: 1px solid var(--rule);
  border-radius: 3px;
  padding: 0.08em 0.34em;
  white-space: nowrap;
}

/* ---------- masthead ---------- */

.masthead {
  border-bottom: 1px solid var(--rule);
  background: var(--panel);
}

.masthead .wrap {
  display: flex;
  align-items: center;
  gap: 24px;
  min-height: 62px;
  flex-wrap: wrap;
}

.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  color: var(--ink);
  text-decoration: none;
  font-weight: 600;
  letter-spacing: 0.02em;
  margin-right: auto;
}

.brand svg { display: block; flex: none; color: var(--accent); }
.brand b { font-weight: 700; }
.brand span { color: var(--ink-faint); font-weight: 400; font-size: 0.82rem; letter-spacing: 0.06em; text-transform: uppercase; }

.nav { display: flex; gap: 20px; flex-wrap: wrap; }

.nav a {
  color: var(--ink-soft);
  text-decoration: none;
  font-size: 0.92rem;
  padding: 4px 0;
  border-bottom: 2px solid transparent;
}

.nav a:hover { color: var(--ink); }
.nav a[aria-current="page"] { color: var(--ink); border-bottom-color: var(--accent); }

/* ---------- hero ---------- */

.hero {
  border-bottom: 1px solid var(--rule);
  background: linear-gradient(180deg, var(--bg-alt), var(--bg));
  padding: 56px 0 48px;
}

.hero h1 {
  font-size: clamp(1.9rem, 5vw, 2.7rem);
  margin: 0 0 4px;
}

.hero .expansion {
  color: var(--ink-soft);
  font-size: clamp(1rem, 2.4vw, 1.18rem);
  margin: 0 0 18px;
}

.hero .lede {
  max-width: 62ch;
  font-size: 1.05rem;
  color: var(--ink-soft);
}

.pill-row { display: flex; flex-wrap: wrap; gap: 10px; margin-top: 22px; }

.pill {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  font-family: var(--mono);
  font-size: 0.76rem;
  letter-spacing: 0.02em;
  padding: 4px 10px;
  border: 1px solid var(--rule-strong);
  border-radius: 100px;
  color: var(--ink-soft);
  background: var(--panel);
}

.pill.is-current { border-color: var(--accent); color: var(--accent); background: var(--accent-soft); }

.dot { width: 6px; height: 6px; border-radius: 50%; background: currentColor; flex: none; }

.btn-row { display: flex; flex-wrap: wrap; gap: 12px; margin-top: 28px; }

.btn {
  display: inline-block;
  padding: 9px 18px;
  border-radius: var(--radius);
  font-size: 0.94rem;
  text-decoration: none;
  border: 1px solid var(--accent);
  background: var(--accent);
  color: var(--bg);
}

@media (prefers-color-scheme: dark) { .btn { color: #10201e; } }

.btn:hover { filter: brightness(1.08); }

.btn.secondary { background: transparent; color: var(--accent); }
.btn.secondary:hover { background: var(--accent-soft); filter: none; }

/* ---------- layout blocks ---------- */

main { padding: 8px 0 64px; }

section + section { margin-top: 8px; }

.grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(230px, 1fr));
  gap: 16px;
  margin: 20px 0 8px;
}

.card {
  border: 1px solid var(--rule);
  border-radius: var(--radius);
  background: var(--panel);
  padding: 18px 20px;
}

.card h3 { margin: 0 0 6px; font-size: 0.98rem; }
.card p { margin: 0; color: var(--ink-soft); font-size: 0.93rem; }

.note {
  border-left: 3px solid var(--rule-strong);
  padding: 2px 0 2px 16px;
  color: var(--ink-soft);
  margin: 20px 0;
}

.note.warn { border-left-color: var(--warn); }
.note strong { color: var(--ink); }

/* ---------- code ---------- */

.code {
  position: relative;
  margin: 18px 0;
  border: 1px solid var(--rule);
  border-radius: var(--radius);
  background: var(--code-bg);
  overflow: hidden;
}

.code-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 7px 12px;
  border-bottom: 1px solid var(--rule);
  font-family: var(--mono);
  font-size: 0.74rem;
  color: var(--ink-faint);
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.copy {
  font: inherit;
  text-transform: inherit;
  letter-spacing: inherit;
  color: var(--ink-faint);
  background: transparent;
  border: 1px solid var(--rule-strong);
  border-radius: 3px;
  padding: 2px 8px;
  cursor: pointer;
}

.copy:hover { color: var(--ink); border-color: var(--ink-faint); }

.code pre {
  margin: 0;
  padding: 14px 16px;
  overflow-x: auto;
  line-height: 1.55;
}

/* ---------- tables ---------- */

.table-scroll { overflow-x: auto; margin: 18px 0; }

table {
  border-collapse: collapse;
  width: 100%;
  min-width: 480px;
  font-size: 0.92rem;
}

th, td {
  text-align: left;
  padding: 9px 14px 9px 0;
  border-bottom: 1px solid var(--rule);
  vertical-align: top;
}

th {
  font-weight: 600;
  font-size: 0.78rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--ink-faint);
  white-space: nowrap;
}

td code { white-space: nowrap; }

/* ---------- spec page ---------- */

.doc { display: grid; grid-template-columns: 210px 1fr; gap: 40px; align-items: start; }

.toc {
  position: sticky;
  top: 24px;
  border-left: 1px solid var(--rule);
  padding-left: 18px;
  font-size: 0.88rem;
}

.toc h4 {
  margin: 0 0 8px;
  font-size: 0.72rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--ink-faint);
}

.toc ol { list-style: none; margin: 0; padding: 0; }
.toc li { margin: 0 0 5px; }
.toc a { color: var(--ink-soft); text-decoration: none; }
.toc a:hover { color: var(--accent); text-decoration: underline; }

.doc h2 { scroll-margin-top: 20px; }

.doc h2 .num, .doc h3 .num {
  color: var(--ink-faint);
  font-weight: 400;
  margin-right: 8px;
}

@media (max-width: 760px) {
  .doc { grid-template-columns: 1fr; gap: 8px; }
  .toc { position: static; border-left: 0; border-bottom: 1px solid var(--rule); padding: 0 0 16px; margin-bottom: 8px; }
  .toc ol { columns: 2; column-gap: 24px; }
}

/* ---------- changelog / faq ---------- */

.release { border-top: 1px solid var(--rule); padding: 22px 0 6px; }
.release:first-of-type { border-top: 0; }

.release-head { display: flex; align-items: baseline; gap: 14px; flex-wrap: wrap; }
.release-head h2 { margin: 0; font-size: 1.15rem; }
.release-head time { color: var(--ink-faint); font-family: var(--mono); font-size: 0.82rem; }

.tag {
  font-family: var(--mono);
  font-size: 0.68rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  padding: 2px 7px;
  border-radius: 3px;
  border: 1px solid var(--rule-strong);
  color: var(--ink-faint);
}

.tag.stable { border-color: var(--accent); color: var(--accent); }
.tag.draft { border-color: var(--warn); color: var(--warn); }

.release ul { margin: 10px 0 0; padding-left: 20px; }
.release li { margin-bottom: 4px; color: var(--ink-soft); }

.qa { border-top: 1px solid var(--rule); padding: 20px 0; }
.qa h2 { margin: 0 0 8px; font-size: 1.05rem; }
.qa p:last-child { margin-bottom: 0; }

/* ---------- footer ---------- */

.foot {
  border-top: 1px solid var(--rule);
  background: var(--bg-alt);
  padding: 30px 0 42px;
  font-size: 0.88rem;
  color: var(--ink-faint);
}

.foot-cols {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 24px;
  margin-bottom: 26px;
}

.foot h4 {
  margin: 0 0 8px;
  font-size: 0.72rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--ink-soft);
}

.foot ul { list-style: none; margin: 0; padding: 0; }
.foot li { margin-bottom: 5px; }
.foot a { color: var(--ink-soft); text-decoration: none; }
.foot a:hover { color: var(--accent); text-decoration: underline; }

.foot-legal { border-top: 1px solid var(--rule); padding-top: 18px; max-width: 70ch; }