/* ============================================================
   jkjin.com — design tokens v2 (mock preview build)
   Framework-agnostic. Paste into any renderer.

   PREVIEW NOTE: this file uses Google Fonts CDN for fast mock
   preview. For production, replace the @import below with the
   self-hosted @font-face blocks documented in design-tokens-v1.md
   and fetch woff2 files per A5.1 (pinned GitHub releases +
   SHA256 checksums in fonts/CHECKSUMS.txt).
   ============================================================ */

/* Preview fonts loaded from Google Fonts CDN.
   - Iowan Old Style — body reading surface (system font on macOS/iOS;
     NOT loaded via webfont; Windows/Linux readers fall back to Palatino
     Linotype / Charter / Georgia via the --font-serif stack).
   - Inter — general UI (headings, card titles, metadata).
   - JetBrains Mono — code.
   - Fraunces — PREVIEW SUBSTITUTE for GT Alpina (used on display name).
     Production must license and self-host GT Alpina from
     https://www.grillitype.com/typeface/gt-alpina.
   - Space Grotesk — PREVIEW SUBSTITUTE for a grotesque family (used on nav).
     Production may license GT Walsheim / GT America or similar; swap the
     --font-nav token declaration below. */
@import url('https://fonts.googleapis.com/css2?family=Source+Serif+4:ital,opsz,wght@0,8..60,200..900;1,8..60,200..900&family=Inter:wght@100..900&family=JetBrains+Mono:wght@100..800&family=Fraunces:ital,opsz,wght@0,9..144,300..900;1,9..144,300..900&family=Space+Grotesk:wght@300..700&family=Noto+Serif+SC:wght@300;400;500&display=swap');

/* ---- Fallback @font-face with metric overrides (Crit-10) ----
   Inter is webfont-loaded; a metric-matched local fallback reduces CLS
   on first paint. Iowan Old Style is a system font with no webfont
   counterpart, so no fallback declaration is needed for it — the
   --font-serif stack below cascades directly to Palatino/Charter/Georgia
   on platforms without Iowan. */
@font-face {
  font-family: 'Inter Fallback';
  src: local('Arial'), local('Helvetica Neue'), local('Segoe UI');
  size-adjust: 107%;
  ascent-override: 90%;
  descent-override: 22%;
  line-gap-override: 0%;
}

:root {
  /* ---------- Font families ---------- */
  /* Body reading surface. Iowan Old Style is Apple-only (macOS 10.10+,
     iOS 7+). Windows/Linux visitors cascade to Palatino Linotype /
     Charter / Georgia. All four are editorial transitional serifs with
     similar measure and proportion. */
  --font-serif: 'Iowan Old Style', 'Palatino Linotype',
                'Charter', Georgia, Cambria, 'Times New Roman', Times, serif;
  --font-sans:  'Inter', 'Inter Fallback', -apple-system, BlinkMacSystemFont,
                'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  --font-mono:  'JetBrains Mono', ui-monospace, 'SF Mono', Menlo,
                Consolas, 'Liberation Mono', monospace;
  --font-math:  'STIX Two Math', 'Latin Modern Math', 'Cambria Math', serif;

  /* Display face — used on the name-en ("Jikai Jin") in the hero. */
  --font-display: 'Fraunces', 'Noto Serif SC', serif;

  /* Body face — used on bio, subtitle, hero links, and by convention any
     long-form prose in .grid-page pages. Source Serif 4 is webfont-loaded;
     Noto Serif SC provides fallback coverage for CJK glyphs mixed inline. */
  --font-body: 'Source Serif 4', 'Noto Serif SC', Georgia, serif;

  /* UI face — used on top-nav (site-header) + general sans chrome.
     Inter is the primary. */
  --font-ui: 'Inter', -apple-system, system-ui, sans-serif;

  /* Navigation / grotesque-sans alias (retained for .venue small-caps). */
  --font-nav: 'GT Walsheim', 'GT America', 'Space Grotesk', 'Inter',
              -apple-system, BlinkMacSystemFont, 'Helvetica Neue', sans-serif;

  /* Note: earlier --color-ink / --color-muted / --color-accent / --color-bg
     tokens were removed in the time-theme update. Hero partial inline
     styles use var(--color-X, var(--ink/--accent/--ink-muted)) with the
     fallback form; deleting the --color-* definitions makes the fallback
     take effect in BOTH light and dark modes consistently. */

  /* ---------- Type scale (17px base, 1.2 modular third) ---------- */
  --fs-caption: 0.833rem;   /* 14.17px — figure captions, metadata */
  --fs-small:   0.875rem;   /* 14.88px — footnotes, TOC items */
  --fs-body:    1rem;       /* 17px base — reading surface */
  --fs-lede:    1.125rem;   /* 19.13px — post ledes, pull-quotes */
  --fs-h4:      1.125rem;   /* 19.13px */
  --fs-h3:      1.35rem;    /* 22.95px */
  --fs-h2:      1.7rem;     /* 28.90px */
  --fs-h1:      2.07rem;    /* 35.20px */
  --fs-display: 2.488rem;   /* 42.30px — homepage hero only */

  /* ---------- Rhythm ---------- */
  --lh-tight:   1.15;       /* h1, h2 */
  --lh-snug:    1.3;        /* h3, h4, lede */
  --lh-body:    1.65;       /* reading */
  --lh-loose:   1.8;        /* captions, TOC */

  --measure:      65ch;     /* reading column max-width */
  --measure-wide: 78ch;     /* homepage grid rows */
  --measure-code: 80ch;     /* code block max-width */

  /* ---------- Weights ---------- */
  --fw-regular:  400;
  --fw-medium:   500;
  --fw-semibold: 600;

  /* ---------- Spacing ---------- */
  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 0.75rem;
  --space-4: 1rem;
  --space-5: 1.5rem;
  --space-6: 2rem;
  --space-8: 3rem;
  --space-12: 4.5rem;

  /* ---------- Light mode palette (time-theme v1 — day) ---------- */
  --bg:             #e0f7fa;    /* light cyan */
  --bg-subtle:      #c5edf2;    /* tinted cyan, harmonizes with --bg */
  --ink:            #171212;    /* deep near-black with burgundy undertone */
  --ink-muted:      #6B6863;    /* text-muted */
  --accent:         #6B1F2A;    /* oxblood / burgundy — links */
  --accent-hover:   #4A1520;    /* darker burgundy (~13:1 on bg, strong hover) */
  --accent-visited: #8A4550;    /* muted burgundy */
  --rule:           #E4DFD7;
  --selection:      #E8D9C4;

  /* ---------- Layout ---------- */
  --radius-sm: 2px;
  --radius-md: 4px;
  --toc-width: 220px;
  --toc-gap:   48px;
}

/* Dark mode via prefers-color-scheme — applies only when JS is disabled.
   When JS is enabled, head.html pre-paint script always sets data-theme
   explicitly (either from localStorage or from clock), which bypasses this
   @media rule via the :not([data-theme='light']) selector. This is
   intentional per the time-theme plan: clock > prefers-color-scheme. */
@media (prefers-color-scheme: dark) {
  :root:not([data-theme='light']):not([data-theme='dark']) {
    --bg:             #161513;
    --bg-subtle:      #1E1C19;
    --ink:            #E8E2D2;
    --ink-muted:      #8A8578;
    --accent:         #D4A55C;
    --accent-hover:   #E6BC7A;
    --accent-visited: #B89878;
    --rule:           #332F28;
    --selection:      #3D342A;
  }
}

/* Dark mode via explicit data-theme — set by clock, toggle, or localStorage */
:root[data-theme='dark'] {
  --bg:             #161513;
  --bg-subtle:      #1E1C19;
  --ink:            #E8E2D2;
  --ink-muted:      #8A8578;
  --accent:         #D4A55C;    /* amber / dark-mode link */
  --accent-hover:   #E6BC7A;    /* brighter amber — hover lifts toward light */
  --accent-visited: #B89878;    /* muted amber */
  --rule:           #332F28;
  --selection:      #3D342A;
}

/* ============================================================
   Baseline element styling
   ============================================================ */

html {
  font-size: 17px;
  -webkit-text-size-adjust: 100%;
  font-feature-settings: 'kern', 'liga', 'calt';
  text-rendering: optimizeLegibility;
}

body {
  font-family: var(--font-serif);
  font-weight: var(--fw-regular);
  line-height: var(--lh-body);
  color: var(--ink);
  background: var(--bg);
  margin: 0;
  transition: background 200ms ease, color 200ms ease;
}

/* Crit-7: oldstyle-nums scoped to reading contexts only */
article, .prose {
  font-variant-numeric: oldstyle-nums proportional-nums;
}

/* Headings: Inter, medium weight, editorial-quiet */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-sans);
  font-weight: var(--fw-medium);
  line-height: var(--lh-tight);
  letter-spacing: -0.01em;
  color: var(--ink);
  margin-top: var(--space-8);
  margin-bottom: var(--space-3);
}
h1 { font-size: var(--fs-h1); letter-spacing: -0.02em; }
h2 { font-size: var(--fs-h2); letter-spacing: -0.015em; }
h3 { font-size: var(--fs-h3); line-height: var(--lh-snug); }
h4 { font-size: var(--fs-h4); line-height: var(--lh-snug);
     font-weight: var(--fw-semibold); }

/* Reading column */
article, .prose {
  max-width: var(--measure);
  margin-inline: auto;
  padding-inline: var(--space-5);
}

/* Paragraphs */
p {
  margin-block: var(--space-4);
  hyphens: auto;
  overflow-wrap: break-word;
}

/* Lede (first paragraph after h1 or class-marked) */
.lede, article > p:first-of-type {
  font-size: var(--fs-lede);
  line-height: var(--lh-snug);
  color: var(--ink);
}

/* Links: underline offset + thin, no color-only links */
a {
  color: var(--accent);
  text-decoration: underline;
  text-decoration-thickness: 1px;
  text-underline-offset: 0.18em;
  text-decoration-color: color-mix(in oklab, var(--accent) 55%, transparent);
  transition: text-decoration-color 120ms ease, color 120ms ease;
}
/* Crit-8: color-mix(in oklab) requires Safari 16.4+ / Chrome 111+ / Firefox 113+ — fine for 2026 */
a:hover {
  color: var(--accent-hover);
  text-decoration-color: var(--accent-hover);
}
a:visited { color: var(--accent-visited); }

@media (prefers-reduced-motion: reduce) {
  a, body { transition: none; }
}

/* Code */
code, pre, kbd, samp {
  font-family: var(--font-mono);
  font-size: 0.92em;
}
:not(pre) > code {
  background: var(--bg-subtle);
  padding: 0.1em 0.35em;
  border-radius: var(--radius-sm);
}
pre {
  background: var(--bg-subtle);
  border: 1px solid var(--rule);
  border-radius: var(--radius-md);
  padding: var(--space-4) var(--space-5);
  overflow-x: auto;
  line-height: 1.55;
  max-width: var(--measure-code);
  margin-inline: auto;
}

/* Math containers */
.math, mjx-container, .katex { font-family: var(--font-math); }

/* Hairline rules */
hr {
  border: 0;
  border-top: 1px solid var(--rule);
  margin-block: var(--space-8);
}

/* Blockquote */
blockquote {
  margin-block: var(--space-5);
  margin-inline: 0;
  padding-inline: var(--space-5);
  border-left: 2px solid var(--rule);
  color: var(--ink-muted);
  font-style: italic;
}

/* Figures */
figure {
  margin: var(--space-6) 0;
}
figure img {
  max-width: 100%;
  height: auto;
  display: block;
  margin-inline: auto;
}
figure figcaption {
  font-family: var(--font-sans);
  font-size: var(--fs-caption);
  line-height: var(--lh-loose);
  color: var(--ink-muted);
  margin-top: var(--space-2);
  text-align: center;
}

/* Lists */
ul, ol { padding-inline-start: var(--space-5); }
li { margin-block: var(--space-2); }

/* Selection */
::selection { background: var(--selection); color: var(--ink); }

/* ============================================================
   Signature detail — auto § section numbering on h2.
   Scoped to .prose-article so list pages (publication list, etc.)
   that wrap in plain <article> do not get counters on their year h2s.
   ============================================================ */
article.prose-article { counter-reset: section; }
article.prose-article h2 { counter-increment: section; position: relative; }
article.prose-article h2::before {
  content: '§ ' counter(section);
  display: block;
  font-family: var(--font-sans);
  font-weight: var(--fw-regular);
  font-size: var(--fs-caption);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--ink-muted);
  margin-bottom: var(--space-2);
}
article.prose-article.no-section-numbers h2::before { content: none; }

/* ============================================================
   Publication action links — shared pill style used by
   layouts/partials/pub-links.html (list + single).
   ============================================================ */
.pub-link {
  color: var(--accent);
  text-decoration: none;
  font-family: var(--font-ui);
  font-size: 0.82rem;
  letter-spacing: 0.02em;
  border-bottom: 1px solid transparent;
  padding-bottom: 1px;
  white-space: nowrap;
  transition: border-color 120ms ease;
}
.pub-link:hover,
.pub-link:focus-visible { border-bottom-color: var(--accent); }
.pub-link + .pub-link { margin-inline-start: 0; }
.pub-actions {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-3);
  align-items: flex-end;
}

/* ============================================================
   §3.5 Markup contract adopters wrap this way:
     <div class="post-layout">
       <article>...content...</article>
       <nav class="toc">...</nav>        // desktop
       OR
       <details class="toc">...</details> // tablet/mobile
     </div>
   ============================================================ */

/* Default: single-column article */
.post-layout {
  max-width: var(--measure);
  margin-inline: auto;
  padding-inline: var(--space-5);
}
.post-layout > article {
  padding-inline: 0;
}

/* Desktop (>=1280px): right-margin sticky TOC in a grid */
@media (min-width: 1280px) {
  .post-layout {
    display: grid;
    grid-template-columns: 1fr minmax(0, var(--measure)) var(--toc-width) 1fr;
    column-gap: var(--toc-gap);
    max-width: none;
    padding-inline: 0;
  }
  .post-layout > article { grid-column: 2; padding-inline: 0; }
  .post-layout > .toc {
    grid-column: 3;
    position: sticky;
    top: var(--space-8);
    align-self: start;
    max-height: calc(100vh - var(--space-12));
    overflow-y: auto;
    font-family: var(--font-sans);
    font-size: var(--fs-small);
    line-height: var(--lh-loose);
    color: var(--ink-muted);
    border-left: 1px solid var(--rule);
    padding-left: var(--space-4);
  }
  .post-layout > .toc h3 {
    font-size: var(--fs-caption);
    font-weight: var(--fw-medium);
    text-transform: uppercase;
    letter-spacing: 0.08em;
    color: var(--ink-muted);
    margin-top: 0;
  }
  .post-layout > .toc ol { list-style: none; padding-inline-start: 0; }
  .post-layout > .toc li { margin-block: var(--space-2); }
  .post-layout > .toc a {
    color: var(--ink-muted);
    text-decoration: none;
    border-bottom: 1px solid transparent;
  }
  .post-layout > .toc a:hover,
  /* Crit-9: aria-current styling is dormant until scroll-spy IntersectionObserver
     is added in the templates plan. Left in place to avoid re-visits. */
  .post-layout > .toc a[aria-current='true'] {
    color: var(--accent);
  }
}

/* Tablet + mobile (<1280px): inline collapsible TOC at article top */
@media (max-width: 1279.98px) {
  details.toc {
    max-width: var(--measure);
    margin: var(--space-5) auto var(--space-8);
    border: 1px solid var(--rule);
    border-radius: var(--radius-md);
    padding: var(--space-3) var(--space-4);
    font-family: var(--font-sans);
    font-size: var(--fs-small);
    color: var(--ink-muted);
  }
  details.toc > summary {
    cursor: pointer;
    font-weight: var(--fw-medium);
    color: var(--ink);
    font-size: var(--fs-small);
    letter-spacing: 0.02em;
  }
  details.toc ol { list-style: none; padding-inline-start: var(--space-4); margin-block: var(--space-3); }
  details.toc li { margin-block: var(--space-1); }
  details.toc a { color: var(--ink-muted); text-decoration: none; }
  details.toc a:hover { color: var(--accent); }
}

/* Mobile (<640px): TOC closed by default — use `open` attr above 640px */
@media (max-width: 639.98px) {
  details.toc:not([data-force-open]) { }
}

/* ============================================================
   Grid-page variant (homepage + publications)
   ============================================================ */
.grid-page {
  max-width: var(--measure-wide);
  margin-inline: auto;
  padding-inline: var(--space-5);
  padding-block: var(--space-8);
  font-family: var(--font-serif);
}
.grid-page .card-title {
  font-family: var(--font-sans);
  font-weight: var(--fw-medium);
  font-size: var(--fs-lede);
  line-height: var(--lh-snug);
  margin: 0;
}
.grid-page .card-meta {
  font-family: var(--font-sans);
  font-size: var(--fs-caption);
  color: var(--ink-muted);
  letter-spacing: 0.02em;
}

/* ============================================================
   Site chrome
   ============================================================ */
.site-header {
  /* Wider than the body measure so the long brand title ("Welcome to
     Jikai Jin's website") sits on one line alongside the full nav. */
  max-width: 96ch;
  margin-inline: auto;
  padding: var(--space-5) var(--space-5) var(--space-4);
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: var(--space-5);
  /* Nav items use --font-ui (Inter); brand below overrides to serif. */
  font-family: var(--font-ui);
  font-size: 0.95rem;
  letter-spacing: -0.005em;
}
.site-header nav a { color: var(--ink-muted); }
.site-header nav {
  display: flex;
  gap: var(--space-5);
  /* Always single row — per user instruction "do not worry about
     exceeding the width of the main text". Items keep their intrinsic
     width (no shrink) and the nav spills past the measure if needed. */
  flex-wrap: nowrap;
  white-space: nowrap;
  overflow-x: visible;
}
.site-header nav a { flex-shrink: 0; }
/* On narrow viewports the whole header strip (brand + nav + theme
   toggle) becomes horizontally scrollable so nothing is clipped —
   the nav itself stays nowrap and items remain visible by scroll. */
@media (max-width: 560px) {
  .site-header {
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
    flex-wrap: nowrap;
    scrollbar-width: none;
  }
  .site-header::-webkit-scrollbar { display: none; }
  .site-header .brand,
  .site-header .theme-toggle { flex-shrink: 0; }
}
.site-header nav a {
  color: var(--ink-muted);
  text-decoration: none;
  /* Match the "Recent News" section-heading style (see widgets/blank.html):
     --font-ui (inherited from .site-header), small caption size, uppercase. */
  font-size: var(--fs-caption);
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.12em;
}
.site-header nav a:hover { color: var(--accent); }

.site-footer {
  max-width: var(--measure-wide);
  margin: var(--space-12) auto var(--space-6);
  padding: var(--space-5);
  border-top: 1px solid var(--rule);
  font-family: var(--font-sans);
  font-size: var(--fs-caption);
  color: var(--ink-muted);
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: var(--space-4);
}

/* Name — used for "Jikai Jin" on the homepage hero.
   Fraunces italic with the SOFT variation axis; falls back to
   PP Editorial New (commercial — license if you want it) then serif. */
.name {
  font-family: 'Source Serif 4', serif;
  font-style: italic;
  font-weight: 600;
  font-size: 4.5rem;
  letter-spacing: -0.02em;
}

/* Theme toggle (simple text button) */
.theme-toggle {
  background: none;
  border: 1px solid var(--rule);
  border-radius: var(--radius-md);
  color: var(--ink-muted);
  font-family: var(--font-nav);
  font-size: var(--fs-caption);
  padding: 0.25em 0.75em;
  cursor: pointer;
  transition: border-color 120ms ease, color 120ms ease;
}
.theme-toggle:hover {
  color: var(--accent);
  border-color: var(--accent);
}

/* ============================================================
   Staged reveal animation (home page only — gated on html.js-ready).
   Hero (id="about") renders instantly; bio paragraphs fade in
   sequentially on a timer, then the post-hero sections fade in.
   Without JS (no html.js-ready class), content stays visible
   (default opacity:1) so SEO and no-JS users see everything.
   Respects prefers-reduced-motion: reduce.
   ============================================================ */
html.js-ready .bio > p,
html.js-ready .grid-page > *:not(#about) {
  opacity: 0;
  transform: translateY(8px);
  transition: opacity 600ms ease, transform 600ms ease;
  will-change: opacity, transform;
}
/* Revealed override — must match or exceed the specificity of the hidden
   rule above. The :not(#about) selector pulls in an ID (1,2,0), so the
   revealed override for the rest-of-page must include :not(#about) too
   or .revealed alone would lose the cascade. */
html.js-ready .bio > p.revealed,
html.js-ready .grid-page > *:not(#about).revealed {
  opacity: 1;
  transform: none;
}
@media (prefers-reduced-motion: reduce) {
  html.js-ready .bio > p,
  html.js-ready .bio > p.revealed,
  html.js-ready .grid-page > *:not(#about),
  html.js-ready .grid-page > *:not(#about).revealed {
    opacity: 1 !important;
    transform: none !important;
    transition: none !important;
  }
}

/* ============================================================
   Print styles (Crit-11)
   ============================================================ */
@media print {
  :root {
    --bg: #FFFFFF;
    --ink: #000000;
    --ink-muted: #333333;
    --accent: #000000;
    --rule: #CCCCCC;
  }
  body { background: #FFFFFF; color: #000000; }
  .site-header nav, .site-footer, details.toc, .post-layout > .toc,
  .theme-toggle { display: none !important; }
  .post-layout { display: block; max-width: none; }
  .post-layout > article { max-width: 65ch; margin-inline: auto; }
  a { color: #000; text-decoration: underline; }
  a[href^="http"]::after {
    content: ' (' attr(href) ')';
    font-size: 0.85em;
    color: #555;
  }
  article.prose-article h2::before { color: #555; }
  pre, code { border: 1px solid #CCC; background: #F5F5F5; }
  figure, pre { break-inside: avoid; }
}