:root {
  color-scheme: light;
  --paper: #f8f7f3;
  --ink: #1f2623;
  --muted: #5b6660;
  --accent: #2f6b58;
  --line: #dfe2dc;
  --rule: #b9c0b9;
  --code-bg: #f0f1ec;
  --head-bg: #eceee8;
  --gap-bg: #fbe6df;
  --gap-ink: #a3402a;
  --pass-bg: #dcefe3;
  --pass-ink: #23693f;
  --fail-bg: #f8dcd4;
  --fail-ink: #a3402a;
  --sans: "Inter", system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  --display: "Archivo", "Inter", system-ui, sans-serif;
  --mono: "JetBrains Mono", ui-monospace, "SFMono-Regular", Menlo, Consolas, monospace;
}

/* Dark theme: follows the system unless the reader picks light or dark with the toggle. */
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    color-scheme: dark;
    --paper: #141816;
    --ink: #e5e9e6;
    --muted: #a0aba5;
    --accent: #7cc4a7;
    --line: #2c3430;
    --rule: #46514b;
    --code-bg: #1c2220;
    --head-bg: #212825;
    --gap-bg: #3b221c;
    --gap-ink: #f29a83;
    --pass-bg: #1d3528;
    --pass-ink: #86d6a6;
    --fail-bg: #43241d;
    --fail-ink: #f29a83;
  }
}

:root[data-theme="dark"] {
  color-scheme: dark;
  --paper: #141816;
  --ink: #e5e9e6;
  --muted: #a0aba5;
  --accent: #7cc4a7;
  --line: #2c3430;
  --rule: #46514b;
  --code-bg: #1c2220;
  --head-bg: #212825;
  --gap-bg: #3b221c;
  --gap-ink: #f29a83;
  --pass-bg: #1d3528;
  --pass-ink: #86d6a6;
  --fail-bg: #43241d;
  --fail-ink: #f29a83;
}

* { box-sizing: border-box; }
[hidden] { display: none !important; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font: 18px/1.75 var(--sans);
  letter-spacing: -0.006em;
  -webkit-font-smoothing: antialiased;
  font-feature-settings: "cv11", "ss01";
}

a { color: var(--accent); text-underline-offset: 0.2em; text-decoration-thickness: 1px; }
a:hover { color: var(--ink); }
:focus-visible { outline: 2px solid var(--accent); outline-offset: 3px; border-radius: 2px; }

.wrap { width: min(820px, calc(100% - 48px)); margin-inline: auto; }

.skip-link { position: absolute; top: -4rem; left: 1rem; padding: 0.5rem 1rem; background: var(--paper); z-index: 10; }
.skip-link:focus { top: 1rem; }

/* Masthead */
.masthead { border-bottom: 1px solid var(--line); }
.masthead-inner { display: flex; align-items: center; justify-content: space-between; height: 64px; padding: 0 24px; }
.wordmark { display: inline-flex; align-items: center; gap: 0.55rem; color: var(--ink); font-weight: 650; font-size: 17px; letter-spacing: -0.02em; text-decoration: none; }
.masthead-actions { display: flex; align-items: center; gap: 16px; }
.repo-link { font-size: 14px; font-weight: 600; text-decoration: none; }
.theme-toggle { display: inline-flex; align-items: center; justify-content: center; width: 36px; height: 36px; padding: 0; border: 1px solid var(--line); border-radius: 8px; background: transparent; color: var(--ink); cursor: pointer; -webkit-tap-highlight-color: transparent; }
@media (hover: hover) { .theme-toggle:hover { background: var(--code-bg); } }
.icon-sun { display: none; }
:root[data-theme="dark"] .icon-sun { display: block; }
:root[data-theme="dark"] .icon-moon { display: none; }
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) .icon-sun { display: block; }
  :root:not([data-theme="light"]) .icon-moon { display: none; }
}

/* Article */
main { padding: 80px 0 72px; }
h1 { margin: 0 auto 22px; max-width: 760px; font-family: var(--display); font-stretch: 112%; font-weight: 800; font-size: clamp(30px, 4.4vw, 48px); line-height: 1.12; letter-spacing: 0.01em; text-transform: uppercase; text-align: center; text-wrap: balance; }
.dek { margin: 0 auto 72px; max-width: 620px; font-size: 19px; line-height: 1.6; color: var(--muted); text-align: center; text-wrap: balance; }
.dek::after { content: ""; display: block; width: 56px; height: 2px; margin: 36px auto 0; background: var(--rule); }
section + section { margin-top: 72px; }
h2 { margin: 0 0 28px; padding-bottom: 12px; border-bottom: 1px solid var(--rule); font-size: 24px; line-height: 1.3; font-weight: 600; letter-spacing: 0.07em; text-transform: uppercase; color: var(--muted); }
p { margin: 0 0 1.3em; }
section > p:last-child { margin-bottom: 0; }

/* Code blocks */
pre.block {
  margin: 1.5em 0;
  padding: 16px 20px;
  background: var(--code-bg);
  border: 1px solid var(--line);
  border-radius: 10px;
  overflow-x: auto;
  white-space: pre;
  font: 13.5px/1.7 var(--mono);
  letter-spacing: 0;
}
pre.block code { font: inherit; }
pre.command { font-weight: 600; }

/* Worked examples */
.demo { margin: 2em 0; padding: 18px 20px; background: var(--code-bg); border: 1px solid var(--line); border-radius: 10px; font-size: 15px; line-height: 1.55; }
.demo code { font: 13.5px/1.6 var(--mono); letter-spacing: 0; white-space: nowrap; }
.defs { display: grid; grid-template-columns: max-content 1fr; gap: 6px 24px; margin: 0; }
.defs > div { display: contents; }
.defs dt { color: var(--muted); }
.defs dd { margin: 0; }
.rules { row-gap: 14px; }
.rules dd { display: flex; flex-direction: column; }
.check { margin-top: 14px; padding-top: 14px; border-top: 1px solid var(--line); }
.check .q { margin: 0 0 6px; color: var(--muted); }
.check .a { margin: 0; display: flex; flex-wrap: wrap; align-items: center; gap: 4px 12px; }
.check .result { font: 13.5px/1.6 var(--mono); letter-spacing: 0; white-space: nowrap; }
.verdict { margin-left: auto; padding: 1px 8px; border-radius: 4px; font: 600 12.5px/1.6 var(--mono); letter-spacing: 0.04em; }
.pass { background: var(--pass-bg); color: var(--pass-ink); }
.fail { background: var(--fail-bg); color: var(--fail-ink); }

/* State table */
.table-wrap { margin: 2em 0; overflow-x: auto; border: 1px solid var(--line); border-radius: 10px; }
table.states { width: 100%; border-collapse: collapse; font-size: 15px; line-height: 1.5; }
.states th, .states td { padding: 11px 16px; text-align: left; }
.states th { background: var(--head-bg); font-weight: 600; vertical-align: bottom; }
.states td { border-top: 1px solid var(--line); }
.states th:nth-child(-n+2), .states td:nth-child(-n+2) { width: 3.5rem; font-family: var(--mono); font-size: 14px; }
.states .forbidden { color: var(--muted); }
.states tr.gap td { background: var(--gap-bg); }
.states tr.gap td:first-child { box-shadow: inset 4px 0 0 var(--gap-ink); }
.states .gap-cell { color: var(--gap-ink); }

.reference { margin-top: 2.5em; padding-top: 1.25em; border-top: 1px solid var(--line); font-size: 14px; line-height: 1.6; color: var(--muted); }
.reference cite { font-style: italic; }

/* Footer */
.site-footer { border-top: 1px solid var(--line); font-size: 14px; color: var(--muted); }
.footer-inner { display: flex; justify-content: space-between; align-items: center; gap: 1rem; padding: 20px 0 28px; }
.footer-links { display: flex; gap: 1.25rem; }
.footer-links a { text-decoration: none; font-weight: 600; }

@media (max-width: 600px) {
  body { font-size: 17px; line-height: 1.7; }
  .wrap { width: calc(100% - 32px); }
  .masthead-inner { padding: 0 16px; }
  main { padding: 48px 0 56px; }
  h1 { margin-bottom: 16px; font-size: 26px; }
  .dek { margin-bottom: 52px; font-size: 17px; }
  .dek::after { margin-top: 28px; }
  section + section { margin-top: 56px; }
  h2 { font-size: 17px; margin-bottom: 22px; padding-bottom: 10px; }
  pre.block { padding: 14px 16px; font-size: 12.5px; }
  .demo { padding: 16px; font-size: 14.5px; }
  .demo code, .check .result { font-size: 13px; }
  .rules { grid-template-columns: 1fr; row-gap: 4px; }
  .rules > div + div > dt { margin-top: 12px; }
  .states th, .states td { padding: 10px 12px; }
}