/* ==========================================================================
   Simic — static site stylesheet
   Vanilla CSS. No build step, no framework, no external assets, no fonts to
   fetch. Theme follows the reader's OS preference via color-scheme +
   light-dark(); there is no toggle because the site ships zero JavaScript.
   ========================================================================== */

:root {
  color-scheme: light dark;

  /* --- Primitives -------------------------------------------------------
     Simic reads blue-green. Hue 225 carries structure, hue 175 carries
     emphasis. OKLCH so the light and dark ramps stay perceptually matched. */
  --ink-050: oklch(0.985 0.004 225);
  --ink-100: oklch(0.955 0.008 225);
  --ink-200: oklch(0.905 0.012 225);
  --ink-300: oklch(0.825 0.016 225);
  /* ink-500 is the light-mode muted text; kept dark enough that muted text
     clears WCAG AA (4.5:1) against --color-bg-subtle, not just --color-bg. */
  --ink-500: oklch(0.495 0.024 225);
  --ink-700: oklch(0.375 0.030 225);
  --ink-850: oklch(0.235 0.026 225);
  --ink-900: oklch(0.185 0.024 225);
  --ink-950: oklch(0.145 0.020 225);

  --teal-400: oklch(0.780 0.110 175);
  --teal-600: oklch(0.560 0.105 175);
  --teal-700: oklch(0.470 0.098 175);

  --amber-400: oklch(0.800 0.105 85);
  --amber-700: oklch(0.520 0.105 85);

  /* --- Semantic tokens (one declaration each) --------------------------- */
  --color-bg:          light-dark(var(--ink-050), var(--ink-950));
  --color-bg-subtle:   light-dark(var(--ink-100), var(--ink-900));
  --color-bg-code:     light-dark(var(--ink-100), var(--ink-850));
  --color-bg-note:     light-dark(oklch(0.965 0.020 175), oklch(0.235 0.030 195));

  --color-text:        light-dark(var(--ink-900), var(--ink-100));
  --color-text-muted:  light-dark(var(--ink-500), var(--ink-300));
  --color-heading:     light-dark(var(--ink-950), var(--ink-050));

  --color-border:      light-dark(var(--ink-200), oklch(0.300 0.020 225));
  --color-border-firm: light-dark(var(--ink-300), oklch(0.380 0.024 225));

  --color-accent:      light-dark(var(--teal-700), var(--teal-400));
  --color-accent-quiet:light-dark(var(--teal-600), oklch(0.660 0.080 175));
  --color-warn:        light-dark(var(--amber-700), var(--amber-400));

  --color-link:        var(--color-accent);
  --color-link-hover:  color-mix(in oklch, var(--color-link) 72%, var(--color-text) 28%);

  /* --- Typography ------------------------------------------------------- */
  --font-body: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue",
               Arial, sans-serif;
  --font-code: ui-monospace, "SFMono-Regular", "JetBrains Mono", "Fira Code",
               Menlo, Consolas, "Liberation Mono", monospace;

  --text-h1: clamp(2rem, 1.45rem + 2.6vw, 3.1rem);
  --text-h2: clamp(1.35rem, 1.18rem + 0.8vw, 1.75rem);
  --text-h3: clamp(1.08rem, 1.02rem + 0.3vw, 1.22rem);

  /* --- Spacing (8px base) ----------------------------------------------- */
  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 1rem;
  --space-4: 1.5rem;
  --space-5: 2rem;
  --space-6: 3rem;
  --space-7: 4.5rem;

  /* --- Layout ------------------------------------------------------------ */
  --measure: 46rem;      /* prose column */
  --page: 62rem;         /* wide elements: tables, diagrams */
  --radius: 4px;
}

/* Explicit reader override, should one ever be wired up. light-dark() does
   the rest, so no palette is duplicated. */
:root[data-theme="light"] { color-scheme: light; }
:root[data-theme="dark"]  { color-scheme: dark; }

/* --- Reset-ish ----------------------------------------------------------- */
*, *::before, *::after { box-sizing: border-box; }

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

body {
  margin: 0;
  background: var(--color-bg);
  color: var(--color-text);
  font-family: var(--font-body);
  font-size: 1rem;
  line-height: 1.65;
  text-underline-offset: 0.15em;
}

img, svg { max-width: 100%; height: auto; }

/* --- Skip link ----------------------------------------------------------- */
.skip-link {
  position: absolute;
  left: var(--space-2);
  top: -3.5rem;
  z-index: 10;
  padding: var(--space-2) var(--space-3);
  background: var(--color-bg-subtle);
  color: var(--color-text);
  border: 1px solid var(--color-border-firm);
  border-radius: var(--radius);
  transition: top 120ms ease-out;
}
.skip-link:focus { top: var(--space-2); }

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

/* --- Links --------------------------------------------------------------- */
a { color: var(--color-link); text-decoration-thickness: 1px; }
a:hover { color: var(--color-link-hover); }

/* --- Page frame ---------------------------------------------------------- */
.masthead {
  border-bottom: 1px solid var(--color-border);
  background: var(--color-bg-subtle);
}

.masthead__inner,
.contentwrap,
.sitefoot__inner {
  max-width: var(--page);
  margin-inline: auto;
  padding-inline: var(--space-3);
}

.masthead__inner {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: var(--space-2) var(--space-5);
  padding-block: var(--space-3);
}

.wordmark {
  font-family: var(--font-code);
  font-size: 1.05rem;
  font-weight: 600;
  letter-spacing: 0.02em;
  color: var(--color-heading);
  text-decoration: none;
}
.wordmark::before {
  content: "◈ ";
  color: var(--color-accent);
}
.wordmark:hover { color: var(--color-accent); }

.sitenav ul {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2) var(--space-4);
  margin: 0;
  padding: 0;
  list-style: none;
  font-size: 0.94rem;
}
.sitenav a {
  text-decoration: none;
  color: var(--color-text-muted);
  padding-block: var(--space-1);
  border-bottom: 2px solid transparent;
}
.sitenav a:hover { color: var(--color-accent); }
.sitenav a[aria-current="page"] {
  color: var(--color-heading);
  border-bottom-color: var(--color-accent);
}

/* --- Main column --------------------------------------------------------- */
main { display: block; }

.contentwrap {
  padding-block: var(--space-6) var(--space-7);
}

/* Prose is narrower than the page; wide blocks opt out with .wide. */
.contentwrap > * { max-width: var(--measure); }
.contentwrap > .wide,
.contentwrap > .cardgrid,
.contentwrap > .pagehead { max-width: none; }

/* --- Headings ------------------------------------------------------------ */
h1, h2, h3, h4 {
  color: var(--color-heading);
  line-height: 1.2;
  text-wrap: balance;
  margin: 0 0 var(--space-3);
}
h1 { font-size: var(--text-h1); letter-spacing: -0.02em; }
h2 {
  font-size: var(--text-h2);
  margin-top: var(--space-6);
  padding-top: var(--space-3);
  border-top: 1px solid var(--color-border);
}
h3 { font-size: var(--text-h3); margin-top: var(--space-5); }
h4 { font-size: 1rem; margin-top: var(--space-4); }

p, ul, ol, dl { margin: 0 0 var(--space-3); }
ul, ol { padding-left: 1.35rem; }
li { margin-bottom: var(--space-2); }
li > ul, li > ol { margin-top: var(--space-2); }

strong { color: var(--color-heading); font-weight: 650; }

/* --- Page head ----------------------------------------------------------- */
.pagehead { margin-bottom: var(--space-5); }
.pagehead h1 { margin-bottom: var(--space-2); }

.tagline {
  font-family: var(--font-code);
  font-size: 0.95rem;
  letter-spacing: 0.01em;
  color: var(--color-accent);
  margin-bottom: var(--space-4);
}

.lede {
  max-width: var(--measure);
  font-size: 1.12rem;
  line-height: 1.6;
  color: var(--color-text);
}

.crumb {
  font-size: 0.88rem;
  color: var(--color-text-muted);
  margin-bottom: var(--space-3);
}
.crumb a { color: var(--color-text-muted); }
.crumb a:hover { color: var(--color-accent); }

/* --- Callouts ------------------------------------------------------------ */
.note {
  max-width: var(--measure);
  margin: var(--space-4) 0;
  padding: var(--space-3) var(--space-4);
  background: var(--color-bg-note);
  border: 1px solid var(--color-border);
  border-left: 3px solid var(--color-accent);
  border-radius: var(--radius);
}
.note > :last-child { margin-bottom: 0; }
.note__label {
  display: block;
  font-family: var(--font-code);
  font-size: 0.78rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--color-accent);
  margin-bottom: var(--space-1);
}
.note--status {
  background: light-dark(oklch(0.975 0.022 85), oklch(0.235 0.028 75));
  border-left-color: var(--color-warn);
}
.note--status .note__label { color: var(--color-warn); }

/* --- Quotes -------------------------------------------------------------- */
blockquote {
  margin: var(--space-4) 0;
  padding: var(--space-1) 0 var(--space-1) var(--space-4);
  border-left: 3px solid var(--color-border-firm);
  color: var(--color-text);
}
blockquote > :last-child { margin-bottom: 0; }

blockquote.canon {
  border-left-color: var(--color-accent);
  font-size: 1.03rem;
}
blockquote cite {
  display: block;
  margin-top: var(--space-2);
  font-size: 0.85rem;
  font-style: normal;
  color: var(--color-text-muted);
}

/* --- Diagrams -------------------------------------------------------------
   Mermaid sources live in tools/diagrams/*.mmd (shared with the PDF pipeline)
   and are PRE-RENDERED into assets/diagrams/ by `tools/diagrams/render.sh site`
   — the mermaid runtime is never shipped. Each diagram has a
   light and a dark SVG; the pair is swapped below on the same rules the colour
   tokens use, so `prefers-color-scheme` AND the [data-theme] override both work.

   The <img> carries alt="" and the accessible name lives on .diagram__frame
   (role="img" + aria-label) so exactly one name is exposed regardless of which
   variant is displayed.

   --dmin is set per diagram inline: the width below which the SVG stops
   shrinking and the frame scrolls instead, because a flowchart scaled to a
   380px viewport has ~6px text. Legibility beats fitting.
   -------------------------------------------------------------------------- */
.diagram { margin: var(--space-4) 0; max-width: var(--page); }

.diagram__frame {
  overflow-x: auto;
  padding-block: var(--space-2);
}

.diagram__img {
  display: block;
  height: auto;
  max-width: 100%;
  min-width: var(--dmin, 0px);   /* beats max-width when the frame is narrower */
  margin-inline: auto;
}

/* Light is the default; dark swaps in exactly where the tokens do. */
.diagram__img--dark { display: none; }

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) .diagram__img--light { display: none; }
  :root:not([data-theme="light"]) .diagram__img--dark  { display: block; }
}

:root[data-theme="dark"] .diagram__img--light { display: none; }
:root[data-theme="dark"] .diagram__img--dark  { display: block; }
:root[data-theme="light"] .diagram__img--light { display: block; }
:root[data-theme="light"] .diagram__img--dark  { display: none; }

/* --- Code ---------------------------------------------------------------- */
code, kbd, samp {
  font-family: var(--font-code);
  font-size: 0.9em;
}

:not(pre) > code {
  background: var(--color-bg-code);
  border: 1px solid var(--color-border);
  border-radius: 3px;
  padding: 0.08em 0.32em;
  overflow-wrap: break-word;
}

pre {
  max-width: var(--page);
  margin: var(--space-4) 0;
  padding: var(--space-3) var(--space-4);
  background: var(--color-bg-code);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  overflow-x: auto;
  font-size: 0.86rem;
  line-height: 1.55;
}
pre code { background: none; border: 0; padding: 0; font-size: inherit; }

figure { margin: var(--space-4) 0; max-width: var(--page); }
figure > pre { margin-top: 0; }
figcaption {
  font-size: 0.85rem;
  color: var(--color-text-muted);
  margin-top: var(--space-2);
}

/* --- Tables -------------------------------------------------------------- */
.tablewrap {
  max-width: var(--page);
  margin: var(--space-4) 0;
  overflow-x: auto;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
}

table {
  width: 100%;
  min-width: 34rem;
  border-collapse: collapse;
  font-size: 0.92rem;
}
caption {
  text-align: left;
  padding: var(--space-2) var(--space-3);
  font-size: 0.85rem;
  color: var(--color-text-muted);
  border-bottom: 1px solid var(--color-border);
}
th, td {
  text-align: left;
  vertical-align: top;
  padding: var(--space-2) var(--space-3);
  border-bottom: 1px solid var(--color-border);
}
thead th {
  color: var(--color-heading);
  font-size: 0.8rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  background: var(--color-bg-subtle);
  white-space: nowrap;
}
tbody tr:last-child td { border-bottom: 0; }
td.name, th.name {
  font-family: var(--font-code);
  color: var(--color-heading);
  white-space: nowrap;
}

/* --- Definition-ish invariant list --------------------------------------- */
.spine {
  max-width: var(--measure);
  margin: var(--space-4) 0;
  padding: 0;
  list-style: none;
}
.spine > li {
  padding: var(--space-3) 0;
  border-top: 1px solid var(--color-border);
  margin: 0;
}
.spine > li:last-child { border-bottom: 1px solid var(--color-border); }
.spine b {
  display: block;
  color: var(--color-heading);
  font-weight: 650;
}
.inv {
  font-family: var(--font-code);
  font-size: 0.78rem;
  letter-spacing: 0.04em;
  color: var(--color-accent);
  white-space: nowrap;
}

/* --- Card grid ----------------------------------------------------------- */
.cardgrid {
  display: grid;
  gap: var(--space-3);
  grid-template-columns: repeat(auto-fit, minmax(15rem, 1fr));
  margin: var(--space-4) 0 var(--space-5);
  padding: 0;
  list-style: none;
}
.cardgrid > li { margin: 0; }

.card {
  display: block;
  height: 100%;
  padding: var(--space-3) var(--space-4);
  background: var(--color-bg-subtle);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  text-decoration: none;
  color: inherit;
}
a.card:hover {
  border-color: var(--color-accent);
  color: inherit;
}
.card h3 {
  margin: 0 0 var(--space-2);
  font-size: 1rem;
  color: var(--color-accent);
}
.card p {
  margin: 0;
  font-size: 0.92rem;
  color: var(--color-text-muted);
}

/* --- Two-column split (armour / forward, healthy / smelly) --------------- */
.split {
  display: grid;
  gap: var(--space-4);
  grid-template-columns: repeat(auto-fit, minmax(18rem, 1fr));
  max-width: var(--page);
  margin: var(--space-4) 0;
}
.split > section > :first-child { margin-top: 0; }

/* --- Footer -------------------------------------------------------------- */
.sitefoot {
  border-top: 1px solid var(--color-border);
  background: var(--color-bg-subtle);
  font-size: 0.9rem;
  color: var(--color-text-muted);
}
.sitefoot__inner {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2) var(--space-5);
  justify-content: space-between;
  padding-block: var(--space-4);
}
.sitefoot p { margin: 0; }
.sitefoot ul {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2) var(--space-4);
  margin: 0;
  padding: 0;
  list-style: none;
}

/* --- Motion -------------------------------------------------------------- */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    transition-duration: 0.01ms !important;
  }
}

/* --- Print --------------------------------------------------------------- */
@media print {
  :root { color-scheme: light; }
  .masthead, .sitefoot, .skip-link { display: none; }
  body { font-size: 11pt; }
  .contentwrap { max-width: none; padding: 0; }
  pre, .tablewrap { border-color: #999; page-break-inside: avoid; }
  /* Always print the light diagram, whatever the screen theme was. */
  .diagram__img--light { display: block !important; }
  .diagram__img--dark  { display: none !important; }
  .diagram__frame { overflow: visible; }
  .diagram__img { min-width: 0 !important; page-break-inside: avoid; }
  a { color: inherit; text-decoration: underline; }
  a[href^="http"]::after { content: " (" attr(href) ")"; font-size: 0.85em; }
}