/* --- themes --- */
:root,
[data-theme="light"] {
  color-scheme: light;
  --paper: #f4f1ec;
  --surface: #ffffff;
  --ink: #1a1a18;
  --muted: #4a4844;
  --rule: #c8c2b8;
  --accent: #1e4a72;
  --accent-hover: #163a5c;
  --accent-bg: #e4ecf4;
  --link: #1e4a72;
  --link-hover: #163a5c;
  --badge-ok-bg: #c8e6ce;
  --badge-ok-fg: #14532d;
  --badge-post-bg: #f5dcc8;
  --badge-post-fg: #6b3410;
  --focus: #1e4a72;
  --skip-bg: #1a1a18;
  --skip-fg: #f4f1ec;
}

[data-theme="dim"] {
  color-scheme: light;
  --paper: #ddd8cf;
  --surface: #ece8e0;
  --ink: #1f1d1a;
  --muted: #45423c;
  --rule: #b5aea2;
  --accent: #2a5078;
  --accent-hover: #1e3d5c;
  --accent-bg: #d4dde8;
  --link: #2a5078;
  --link-hover: #1e3d5c;
  --badge-ok-bg: #b8d4be;
  --badge-ok-fg: #14532d;
  --badge-post-bg: #e8cdb8;
  --badge-post-fg: #5c3010;
  --focus: #2a5078;
  --skip-bg: #1f1d1a;
  --skip-fg: #ece8e0;
}

[data-theme="dark"] {
  color-scheme: dark;
  --paper: #141412;
  --surface: #1e1e1c;
  --ink: #ece9e4;
  --muted: #b8b4ac;
  --rule: #3a3834;
  --accent: #7eb8e8;
  --accent-hover: #a8d4f8;
  --accent-bg: #243040;
  --link: #8ec8f0;
  --link-hover: #b8e0ff;
  --badge-ok-bg: #1e4a2e;
  --badge-ok-fg: #a8e8b8;
  --badge-post-bg: #4a3020;
  --badge-post-fg: #f0d0b0;
  --focus: #8ec8f0;
  --skip-bg: #ece9e4;
  --skip-fg: #141412;
}

:root {
  --font-scale: 1;
  --mono: 'IBM Plex Mono', ui-monospace, monospace;
  --serif: 'Literata', Georgia, serif;
  --focus-ring: 0 0 0 3px color-mix(in srgb, var(--focus) 35%, transparent);
}

* { box-sizing: border-box; margin: 0; padding: 0; }

html {
  font-size: calc(100% * var(--font-scale));
  scroll-behavior: smooth;
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
}

body {
  display: grid;
  grid-template-columns: minmax(12rem, 220px) 1fr;
  min-height: 100vh;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--serif);
  font-size: 1.05rem;
  line-height: 1.65;
}

/* screen reader only */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

.skip-link {
  position: absolute;
  top: 0.5rem;
  left: 0.5rem;
  z-index: 100;
  padding: 0.6rem 1rem;
  background: var(--skip-bg);
  color: var(--skip-fg);
  font-family: var(--mono);
  font-size: 0.8rem;
  text-decoration: none;
  border-radius: 2px;
  transform: translateY(-200%);
  transition: transform 0.15s;
}

.skip-link:focus {
  transform: translateY(0);
  outline: 3px solid var(--focus);
  outline-offset: 2px;
}

a:focus-visible,
button:focus-visible,
input:focus-visible,
.code-block:focus-visible {
  outline: 3px solid var(--focus);
  outline-offset: 2px;
}

a {
  color: var(--link);
  text-decoration-thickness: 1px;
  text-underline-offset: 0.15em;
}

a:hover {
  color: var(--link-hover);
}

@media (max-width: 800px) {
  body { grid-template-columns: 1fr; }
  .toc {
    position: static !important;
    height: auto !important;
    border-bottom: 1px solid var(--rule);
    padding: 1rem 1.5rem !important;
  }
  .toc nav { display: flex; flex-wrap: wrap; gap: 0.5rem 1rem; }
  .toc .meta { display: none; }
}

.toc {
  position: sticky;
  top: 0;
  height: 100vh;
  overflow-y: auto;
  padding: 2rem 1.25rem;
  border-right: 1px solid var(--rule);
  font-family: var(--mono);
  font-size: 0.7rem;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.back {
  display: block;
  color: var(--muted);
  text-decoration: none;
  margin-bottom: 0.5rem;
  min-height: 2.75rem;
  line-height: 2.75rem;
}

.back:hover { color: var(--accent); }

.toc-title {
  font-size: 0.65rem;
  font-weight: 500;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--muted);
  margin-bottom: 0.25rem;
}

.toc nav {
  display: flex;
  flex-direction: column;
  gap: 0.15rem;
}

.toc nav a {
  color: var(--ink);
  text-decoration: none;
  padding: 0.35rem 0.25rem;
  min-height: 2.75rem;
  display: flex;
  align-items: center;
  border-radius: 2px;
}

.toc nav a:hover { color: var(--accent); }

.toc nav a.is-active {
  font-weight: 600;
  color: var(--accent);
  background: var(--accent-bg);
}

/* preferences */
.prefs {
  margin-top: auto;
  padding-top: 1rem;
  border-top: 1px solid var(--rule);
}

.prefs-heading {
  font-size: 0.65rem;
  font-weight: 500;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--muted);
  margin-bottom: 0.6rem;
}

.theme-field {
  border: 0;
  margin: 0 0 0.75rem;
  padding: 0;
}

.theme-legend {
  font-size: 0.62rem;
  color: var(--muted);
  margin-bottom: 0.35rem;
}

.theme-options {
  display: flex;
  gap: 0.25rem;
}

.theme-option {
  flex: 1;
  cursor: pointer;
}

.theme-option input {
  position: absolute;
  opacity: 0;
  width: 0;
  height: 0;
}

.theme-option span {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 2.75rem;
  padding: 0.35rem 0.25rem;
  border: 1px solid var(--rule);
  background: var(--surface);
  color: var(--ink);
  text-align: center;
  border-radius: 2px;
  transition: background 0.12s, border-color 0.12s;
}

.theme-option input:checked + span {
  border-color: var(--accent);
  background: var(--accent-bg);
  font-weight: 600;
  color: var(--accent);
}

.theme-option input:focus-visible + span {
  outline: 3px solid var(--focus);
  outline-offset: 2px;
}

.font-controls {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.35rem 0.5rem;
}

.font-label {
  width: 100%;
  font-size: 0.62rem;
  color: var(--muted);
}

.font-buttons {
  display: flex;
  gap: 0.25rem;
}

.font-btn {
  font-family: var(--mono);
  font-size: 0.75rem;
  min-width: 2.75rem;
  min-height: 2.75rem;
  padding: 0.35rem 0.5rem;
  border: 1px solid var(--rule);
  background: var(--surface);
  color: var(--ink);
  cursor: pointer;
  border-radius: 2px;
}

.font-btn:hover:not(:disabled) {
  background: var(--accent-bg);
  border-color: var(--accent);
}

.font-btn:disabled {
  opacity: 0.45;
  cursor: not-allowed;
}

.font-scale-readout {
  font-size: 0.62rem;
  color: var(--muted);
  min-width: 2.5rem;
}

.meta {
  margin-top: 0.75rem;
  color: var(--muted);
  line-height: 1.5;
}

.main {
  min-width: 0;
}

.rfc {
  max-width: 42rem;
  padding: 3rem 2.5rem 5rem;
}

@media (max-width: 600px) {
  .rfc { padding: 2rem 1.25rem 4rem; }
}

.rfc-header {
  margin-bottom: 2.5rem;
  padding-bottom: 1.5rem;
  border-bottom: 2px solid var(--ink);
}

.category {
  font-family: var(--mono);
  font-size: 0.7rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--muted);
  margin-bottom: 0.5rem;
}

.rfc-header h1 {
  font-size: 1.75rem;
  font-weight: 600;
  line-height: 1.25;
  margin-bottom: 1.25rem;
}

.rfc-meta {
  width: 100%;
  font-size: 0.85rem;
  border-collapse: collapse;
}

.rfc-meta th {
  text-align: left;
  font-family: var(--mono);
  font-weight: 500;
  color: var(--muted);
  padding: 0.25rem 1rem 0.25rem 0;
  width: 5rem;
}

.badge {
  font-family: var(--mono);
  font-size: 0.65rem;
  padding: 0.15rem 0.45rem;
  background: var(--badge-ok-bg);
  color: var(--badge-ok-fg);
  letter-spacing: 0.04em;
}

.badge.muted {
  background: var(--rule);
  color: var(--muted);
}

section {
  margin-bottom: 2.5rem;
  scroll-margin-top: 2rem;
}

section h2 {
  font-size: 1.15rem;
  font-weight: 600;
  margin-bottom: 0.75rem;
  display: flex;
  align-items: baseline;
  gap: 0.35rem;
}

.sec-num { font-family: var(--mono); font-weight: 500; color: var(--muted); }

section p { margin-bottom: 0.75rem; color: var(--ink); }

.code-block {
  background: var(--accent-bg);
  border: 1px solid var(--rule);
  padding: 1rem 1.25rem;
  margin: 1rem 0;
  overflow-x: auto;
}

.code-block code {
  font-family: var(--mono);
  font-size: 0.8rem;
  line-height: 1.5;
  color: var(--accent);
}

.endpoint {
  border: 1px solid var(--rule);
  margin: 1.25rem 0;
  background: var(--surface);
}

.endpoint-head {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.5rem 0.75rem;
  padding: 0.75rem 1rem;
  background: var(--accent-bg);
  border-bottom: 1px solid var(--rule);
  font-family: var(--mono);
  font-size: 0.8rem;
}

.method {
  font-weight: 600;
  color: var(--badge-ok-fg);
  background: var(--badge-ok-bg);
  padding: 0.15rem 0.4rem;
  font-size: 0.7rem;
}

.path { color: var(--accent); font-weight: 500; }

.ext { margin-left: auto; font-size: 0.75rem; }
.ext a { color: var(--muted); }
.ext a:hover { color: var(--link); }

.endpoint > p,
.endpoint > ul {
  padding: 0.75rem 1rem;
  font-size: 0.95rem;
}

.endpoint ul {
  padding-top: 0;
  padding-left: 2rem;
  color: var(--muted);
  font-size: 0.85rem;
}

.table-wrap {
  overflow-x: auto;
  margin-top: 0.75rem;
  -webkit-overflow-scrolling: touch;
}

.spec-table {
  width: 100%;
  min-width: 20rem;
  border-collapse: collapse;
  font-size: 0.9rem;
}

.spec-table th,
.spec-table td {
  border: 1px solid var(--rule);
  padding: 0.5rem 0.75rem;
  text-align: left;
}

.spec-table th {
  font-family: var(--mono);
  font-size: 0.75rem;
  background: var(--accent-bg);
  font-weight: 500;
}

.spec-table code {
  font-family: var(--mono);
  font-size: 0.8rem;
  color: var(--accent);
}

.spec-table a { color: var(--link); }

.contact-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
  margin: 1.25rem 0;
}

@media (max-width: 500px) {
  .contact-grid { grid-template-columns: 1fr; }
}

.contact-card {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
  padding: 1rem;
  border: 2px solid var(--ink);
  text-decoration: none;
  color: var(--ink);
  font-family: var(--mono);
  font-size: 0.85rem;
  transition: background 0.15s;
  min-height: 2.75rem;
}

.contact-card:hover,
.contact-card:focus-visible {
  background: var(--accent-bg);
}

.method.post {
  font-weight: 600;
  color: var(--badge-post-fg);
  background: var(--badge-post-bg);
  align-self: flex-start;
  padding: 0.1rem 0.35rem;
  font-size: 0.65rem;
}

.contact-card .desc {
  font-family: var(--serif);
  font-size: 0.9rem;
  color: var(--muted);
}

.copyright {
  font-size: 0.8rem;
  color: var(--muted);
  margin-top: 2rem;
}