/* Above-the-fold critical reset + dark-mode body background.
   Phase 17: extracted from post.html shell's inline <style> block (113 files × 533 bytes = 60KB).
   Must remain in CSS so it loads BEFORE React mounts, preventing FOUC.
   Do NOT hide .seo-fallback with body.js-ready — see the note at the end of this file. */
html,body{margin:0;padding:0;background:var(--cream, #faf7f1);}
body.dark, html.dark { background: var(--cream, #1a1d24) !important; }

.seo-fallback { max-width: 720px; margin: 0 auto; padding: 2rem 1.5rem; font-family: 'Noto Sans TC', sans-serif; color: #3e3f42; line-height: 1.8; }
  .seo-fallback h1 { font-family: 'Noto Serif TC', serif; font-size: 1.8rem; margin-bottom: 0.5rem; color: #15171a; }
  .seo-fallback .meta { color: #666; font-size: 0.9rem; margin-bottom: 1.5rem; }
  .seo-fallback .meta .author { font-weight: 600; color: #a1431d; }
  .seo-fallback .cat { display: inline-block; background: #a1431d; color: #fff; padding: 2px 10px; border-radius: 4px; font-size: 0.8rem; margin-bottom: 0.75rem; }
  .seo-fallback article { font-size: 1rem; }
  .seo-fallback article h2 { font-family: 'Noto Serif TC', serif; font-size: 1.4rem; margin: 2rem 0 0.75rem; color: #15171a; border-bottom: 2px solid #ece9e3; padding-bottom: 0.3rem; }
  .seo-fallback article h3 { font-family: 'Noto Serif TC', serif; font-size: 1.15rem; margin: 1.5rem 0 0.5rem; }
  .seo-fallback article p { margin: 0.75rem 0; }
  .seo-fallback article ul, .seo-fallback article ol { margin: 0.5rem 0; padding-left: 1.5rem; }
  .seo-fallback article li { margin: 0.3rem 0; }
  .seo-fallback article blockquote { border-left: 4px solid #a1431d; margin: 1rem 0; padding: 0.5rem 1rem; background: #faf7f1; color: #555; }
  .seo-fallback article pre { background: #f5f5f5; padding: 1rem; border-radius: 6px; overflow-x: auto; font-size: 0.9rem; }
  .seo-fallback article code { font-family: 'JetBrains Mono', monospace; font-size: 0.9em; }
  .seo-fallback article img { max-width: 100%; height: auto; border-radius: 8px; margin: 1rem 0; }
  .seo-fallback article table { border-collapse: collapse; width: 100%; margin: 1rem 0; }
  .seo-fallback article th, .seo-fallback article td { border: 1px solid #ddd; padding: 8px 12px; text-align: left; }
  .seo-fallback article th { background: #f5f5f5; }
  .seo-fallback .back { display: inline-block; margin-top: 2rem; color: #a1431d; text-decoration: none; font-weight: 600; }
  .seo-fallback .back:hover { text-decoration: underline; }
  .seo-author-box { display: flex; align-items: center; gap: 1rem; background: #faf7f1; border-radius: 12px; padding: 1rem 1.25rem; margin-top: 2.5rem; border: 1px solid #ece9e3; }
  .seo-author-box img { width: 48px; height: 48px; border-radius: 50%; }
  .seo-author-box .name { font-weight: 700; color: #15171a; }
  .seo-author-box .desc { font-size: 0.85rem; color: #666; }
  .article-toc { background: #faf7f1; border: 1px solid #ece9e3; border-left: 4px solid #a1431d; border-radius: 8px; padding: 1rem 1.25rem; margin: 0 0 2rem 0; font-size: 0.92rem; }
  .article-toc .toc-title { font-family: 'Noto Serif TC', serif; font-size: 1rem; margin: 0 0 0.5rem; color: #15171a; }
  .article-toc .toc-list { list-style: none; padding: 0; margin: 0; }
  .article-toc .toc-list li { margin: 0.25rem 0; }
  .article-toc .toc-list li.toc-sub { padding-left: 1.25rem; font-size: 0.88rem; color: #555; }
  .article-toc .toc-list a { color: #a1431d; text-decoration: none; }
  .article-toc .toc-list a:hover { text-decoration: underline; }
  .post-ad-slot { margin: 2rem 0; padding: 1rem 0; min-height: 90px; border-top: 1px dashed #ece9e3; border-bottom: 1px dashed #ece9e3; text-align: center; color: #999; font-size: 0.8rem; }
/* Deliberately NO `body.js-ready .seo-fallback{display:none}` here (removed 2026-10-21).
   post.html adds `js-ready` on the SAME tick as ReactDOM.createRoot().render(), but a
   React 18 concurrent-root commit lands ~250ms later: that window rendered an empty page
   (measured desktop CLS 0.189 on /post/least-squares-proof-calculus, 3 of 6 loads).
   React's first commit replaces #root's children atomically, so the fallback disappears
   together with the real page and needs no CSS helper. If React ever fails to mount, the
   fallback now stays visible — which is the behaviour we want. */

/* ============ REACT PAGES SEO FALLBACK CARD ============ */
/* Phase 13: extracted from 116+ inline style= attributes across
   index.html / blog.html / english.html. Saves ~77KB across 3 HTMLs. */
.seo-fallback-card { background:#fff;border:1px solid #ece9e3;border-radius:12px;padding:1.25rem;margin-bottom:1rem; }
.seo-fallback-h2 { font-family:'Noto Serif TC',serif;font-size:1.4rem;color:#15171a;border-bottom:2px solid #ece9e3;padding-bottom:0.3rem;margin:2rem 0 1rem; }
.seo-fallback-h2-lg { font-family:'Noto Serif TC',serif;font-size:1.5rem;color:#15171a;border-bottom:2px solid #ece9e3;padding-bottom:0.5rem;margin:2rem 0 1rem; }
.seo-fallback-h1 { font-family:'Noto Serif TC',serif;font-size:2rem;color:#15171a; }
.seo-fallback-accent { color:#a1431d; }
.seo-fallback-accent-strong { color:#a1431d;font-weight:600; }
.seo-fallback-cta-link { display:inline-block;color:#a1431d;font-weight:600;margin-top:0.5rem; }
.seo-fallback-snippet { font-size:0.9rem;color:#666;margin:0.3rem 0; }
.seo-fallback-date { font-size:0.8rem;color:#999; }
.seo-fallback-h3 { font-family:'Noto Serif TC',serif;font-size:1.1rem;margin:0.5rem 0; }
.seo-fallback-a { color:#15171a;text-decoration:none; }
.seo-fallback-cat { display:inline-block;color:#fff;padding:2px 10px;border-radius:4px;font-size:0.8rem;margin-bottom:0.5rem; }
.seo-fallback-cat-en { background:#b15a36; }
.seo-fallback-cat-math { background:#35608c; }
.seo-fallback-cat-other { background:#a1431d; }


/* ============ REACT PAGES SEO FALLBACK DARK MODE ============ */
/* Inline-style overrides for SEO fallback content on index / about / blog /
   math / english / learning-path / privacy / terms / contact. These were
   previously inlined in each HTML's <style> block (~17KB total). Cached once
   here so the HTML stays small and the styles stay in sync via dark-rules.css
   variable tokens. */

body.dark .seo-fallback h1[style*="color:#15171a"],
html.dark .seo-fallback h1[style*="color:#15171a"],
body.dark .seo-fallback h2[style*="color:#15171a"],
html.dark .seo-fallback h2[style*="color:#15171a"],
body.dark .seo-fallback h3[style*="color:#15171a"],
html.dark .seo-fallback h3[style*="color:#15171a"],
body.dark .seo-fallback h3 a[style*="color:#15171a"],
html.dark .seo-fallback h3 a[style*="color:#15171a"],
body.dark .seo-fallback .seo-fallback-h3,
body.dark .seo-fallback .seo-fallback-h3 a,
html.dark .seo-fallback .seo-fallback-h3,
html.dark .seo-fallback .seo-fallback-h3 a { color: var(--ink); }

body.dark .seo-fallback p[style*="color:#3e3f42"],
html.dark .seo-fallback p[style*="color:#3e3f42"],
body.dark .seo-fallback ul[style*="color:#3e3f42"],
html.dark .seo-fallback ul[style*="color:#3e3f42"],
body.dark .seo-fallback li[style*="color:#3e3f42"],
html.dark .seo-fallback li[style*="color:#3e3f42"] { color: var(--soft); }

body.dark .seo-fallback p[style*="color:#666"],
html.dark .seo-fallback p[style*="color:#666"],
body.dark .seo-fallback .seo-fallback-snippet,
html.dark .seo-fallback .seo-fallback-snippet { color: var(--soft); }

body.dark .seo-fallback span[style*="color:#999"],
html.dark .seo-fallback span[style*="color:#999"],
body.dark .seo-fallback .seo-fallback-date,
html.dark .seo-fallback .seo-fallback-date { color: var(--muted); }

body.dark .seo-fallback a[style*="color:#a1431d"],
html.dark .seo-fallback a[style*="color:#a1431d"] { color: var(--accent); }

body.dark .seo-fallback h2[style*="border-bottom"],
html.dark .seo-fallback h2[style*="border-bottom"],
body.dark .seo-fallback nav[style*="border-top"],
html.dark .seo-fallback nav[style*="border-top"] { border-color: var(--line); }

body.dark .seo-fallback div[style*="background:#fff"],
html.dark .seo-fallback div[style*="background:#fff"],
body.dark .seo-fallback div[style*="background:#faf7f1"],
html.dark .seo-fallback div[style*="background:#faf7f1"],
body.dark .seo-fallback .seo-fallback-card,
html.dark .seo-fallback .seo-fallback-card {
  background: var(--paper);
  border-color: var(--line);
}

body.dark footer p[style*="color:#999"],
html.dark footer p[style*="color:#999"],
body.dark footer p[style*="color:#666"],
html.dark footer p[style*="color:#666"] { color: var(--muted); }

body.dark footer a[style*="color:#a1431d"],
html.dark footer a[style*="color:#a1431d"] { color: var(--accent); }

body.dark, html.dark { background: var(--cream); }

/* Mermaid-style SVG diagram (replaces inline mermaid blocks now that mermaid.min.js is dropped).
   Used by posts that previously had <pre><code class="language-mermaid"> — e.g. euler-line-nine-point-circle. */
.seo-fallback .mermaid-diagram,
.ww-article .mermaid-diagram {
  display: block;
  margin: 1.5rem auto;
  padding: 1.25rem;
  background: var(--paper, #ffffff);
  border: 1px solid var(--line, #ece9e3);
  border-radius: 8px;
  text-align: center;
  max-width: 520px;
}
.seo-fallback .mermaid-diagram svg,
.ww-article .mermaid-diagram svg { max-width: 100%; height: auto; }
body.dark .seo-fallback .mermaid-diagram,
html.dark .seo-fallback .mermaid-diagram,
body.dark .ww-article .mermaid-diagram,
html.dark .ww-article .mermaid-diagram {
  background: var(--paper, #22252d);
  border-color: var(--line, #2e323b);
}