/* ==========================================================================
   Blog design system — warm paper, deep teal accent, Noto Sans + JetBrains Mono
   Used by _layouts/blog.html (posts, /blogs/, /archives/). The academic pages
   keep their own styles.
   ========================================================================== */

:root {
  --bg: #FBFAF6;
  --panel: #FFFFFF;
  --bg-dim: #F3F1E9;
  --ink: #201F1B;
  --ink-2: #52504A;
  --ink-3: #8C877B;
  --rule: #E6E2D6;
  --rule-soft: #EEEAE0;
  --accent: #0E7568;
  --accent-ink: #0A5A50;
  --accent-tint: #E9F1EE;
  --rust: #C0552B;
  --sans: "Noto Sans", "Noto Sans SC", -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --mono: "JetBrains Mono", ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  --col: 45rem;
}

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

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

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 17px;
  line-height: 1.62;
  font-feature-settings: "kern" 1;
  text-rendering: optimizeLegibility;
}

::selection { background: var(--accent-tint); color: var(--accent-ink); }

[id] { scroll-margin-top: 5rem; }

/* ── Header ─────────────────────────────────────────────────────────── */

.bp-header {
  position: sticky;
  top: 0;
  z-index: 20;
  background: rgba(251, 250, 246, 0.92);
  -webkit-backdrop-filter: blur(8px);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--rule);
}

.bp-header-inner {
  max-width: var(--col);
  margin: 0 auto;
  padding: 0.85rem 1.4rem;
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 1rem;
}

.bp-brand {
  font-weight: 700;
  font-size: 1.02rem;
  letter-spacing: -0.01em;
  color: var(--ink);
  text-decoration: none;
  white-space: nowrap;
}

.bp-brand:hover { color: var(--accent-ink); }

.bp-brand-sub {
  margin-left: 0.55rem;
  font-family: var(--mono);
  font-size: 0.66rem;
  font-weight: 600;
  letter-spacing: 0.16em;
  color: var(--accent);
  text-transform: uppercase;
}

.bp-nav {
  display: flex;
  gap: 1.3rem;
  flex-wrap: wrap;
}

.bp-nav a {
  font-family: var(--mono);
  font-size: 0.72rem;
  font-weight: 500;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--ink-2);
  text-decoration: none;
}

.bp-nav a:hover, .bp-nav a.active { color: var(--accent); }

/* ── Main column ────────────────────────────────────────────────────── */

.bp-main {
  max-width: var(--col);
  margin: 0 auto;
  padding: 3.2rem 1.4rem 0;
}

/* ── Post header ────────────────────────────────────────────────────── */

.bp-title {
  margin: 0 0 0.9rem;
  font-size: clamp(1.75rem, 4.4vw, 2.35rem);
  font-weight: 750;
  line-height: 1.18;
  letter-spacing: -0.02em;
}

.bp-meta {
  display: flex;
  align-items: baseline;
  flex-wrap: wrap;
  gap: 0.3rem 0.65rem;
  font-family: var(--mono);
  font-size: 0.74rem;
  font-weight: 500;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--ink-3);
}

.bp-meta a { color: inherit; text-decoration: none; }
.bp-meta .bp-tag { color: var(--accent); }
.bp-post-header { margin-bottom: 2.6rem; padding-bottom: 1.6rem; border-bottom: 1px solid var(--rule); }

/* ── Content typography ─────────────────────────────────────────────── */

.bp-content { color: #2B2A25; }

.bp-content > p:first-child { font-size: 1.02em; }

.bp-content h1, .bp-content h2, .bp-content h3,
.bp-content h4, .bp-content h5, .bp-content h6 {
  color: var(--ink);
  line-height: 1.3;
  letter-spacing: -0.012em;
  scroll-margin-top: 5rem;
}

/* Some older posts use # (h1) for sections — render it like h2. */
.bp-content h1, .bp-content h2 {
  margin: 2.4em 0 0.65em;
  font-size: 1.5rem;
  font-weight: 700;
}

.bp-content h3 { margin: 2em 0 0.5em; font-size: 1.2rem; font-weight: 650; }
.bp-content h4 { margin: 1.7em 0 0.45em; font-size: 1.04rem; font-weight: 650; }
.bp-content h5, .bp-content h6 { margin: 1.7em 0 0.5em; font-size: 0.95rem; font-weight: 650; }

.bp-content p { margin: 0 0 1.05em; }

.bp-content a {
  color: inherit;
  text-decoration: underline;
  text-decoration-color: rgba(14, 117, 104, 0.45);
  text-decoration-thickness: 1px;
  text-underline-offset: 3px;
}

.bp-content a:hover { color: var(--accent-ink); text-decoration-color: var(--accent); }

.bp-content ul, .bp-content ol { margin: 0 0 1.05em; padding-left: 1.5em; }
.bp-content li { margin-bottom: 0.22em; }
.bp-content li > ul, .bp-content li > ol { margin: 0.22em 0; }

.bp-content blockquote {
  margin: 1.7em 0;
  padding: 0.15em 1.35em;
  border-left: 3px solid var(--accent);
  color: var(--ink-2);
}

.bp-content blockquote p:last-child { margin-bottom: 0; }
.bp-content blockquote p:first-child { margin-top: 0.6em; }

.bp-content hr {
  margin: 3em auto;
  border: 0;
  border-top: 1px solid var(--rule);
}

.bp-content img { max-width: 100%; height: auto; }

.bp-content center { display: block; margin: 1.6em 0; }
.bp-content center img { margin: 0 auto; }

.bp-content figure { margin: 1.8em 0; }

.bp-content strong { color: var(--ink); }

/* ── Code ───────────────────────────────────────────────────────────── */

.bp-content code {
  font-family: var(--mono);
  font-size: 0.845em;
  background: var(--bg-dim);
  border: 1px solid var(--rule-soft);
  border-radius: 4px;
  padding: 0.08em 0.35em;
}

.bp-content pre {
  margin: 0;
  overflow-x: auto;
  font-family: var(--mono);
  font-size: 0.8rem;
  line-height: 1.55;
}

.bp-content pre code {
  background: none;
  border: 0;
  border-radius: 0;
  padding: 0;
  font-size: 1em;
}

.bp-content div.highlighter-rouge,
.bp-content figure.highlight,
.bp-content pre.highlight {
  margin: 1.5em 0;
}

.bp-content .highlight {
  background: var(--bg-dim);
  border: 1px solid var(--rule);
  border-radius: 8px;
}

.bp-content .highlight pre { padding: 0.95rem 1.1rem; background: transparent; border: 0; }
.bp-content .highlight .highlight { border: 0; border-radius: 0; background: transparent; }
.bp-content .highlight .err { background: transparent; color: inherit; }

/* Plain (non-rouge) pre blocks, e.g. ```text fences */
.bp-content pre:not(.highlight):not([class*="language"]) {
  background: var(--bg-dim);
  border: 1px solid var(--rule);
  border-radius: 8px;
  padding: 0.95rem 1.1rem;
}

/* ── Tables ─────────────────────────────────────────────────────────── */

.bp-content table {
  display: block;
  width: max-content;
  max-width: 100%;
  overflow-x: auto;
  margin: 1.7em 0;
  border-collapse: collapse;
  font-size: 0.9em;
  line-height: 1.55;
}

.bp-content th {
  font-family: var(--mono);
  font-size: 0.68rem;
  font-weight: 600;
  letter-spacing: 0.07em;
  text-transform: uppercase;
  color: var(--ink-2);
  background: var(--bg-dim);
  text-align: left;
}

.bp-content th, .bp-content td {
  padding: 0.5rem 0.8rem;
  border: 1px solid var(--rule);
}

/* ── Math (KaTeX) ───────────────────────────────────────────────────── */

.bp-content .katex { font-size: 1.06em; }

.bp-content .katex-display {
  margin: 1.9em 0;
  padding: 0.15em 0;
  overflow-x: auto;
  overflow-y: hidden;
}

/* ── TL;DR callout ──────────────────────────────────────────────────── */

.bp-tldr {
  margin: 0 0 2rem;
  padding: 0.95rem 1.25rem;
  background: var(--panel);
  border: 1px solid var(--rule);
  border-left: 3px solid var(--accent);
  border-radius: 0 8px 8px 0;
  font-size: 0.95em;
  line-height: 1.6;
  color: var(--ink-2);
}

.bp-tldr .bp-tldr-tag {
  font-family: var(--mono);
  font-size: 0.68rem;
  font-weight: 600;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--accent-ink);
  margin-right: 0.5rem;
}

.bp-tldr p { margin: 0 0 0.6em; }
.bp-tldr p:last-child { margin-bottom: 0; }

/* ── Collapsible table of contents ──────────────────────────────────── */

.bp-content .bp-toc {
  margin: 2em 0;
  border: 1px solid var(--rule);
  border-radius: 8px;
  background: var(--panel);
  padding: 0.8rem 1.15rem;
}

.bp-content .bp-toc summary {
  cursor: pointer;
  user-select: none;
  list-style: none;
  display: flex;
  align-items: center;
  gap: 0.65rem;
  font-family: var(--mono);
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--ink-2);
}

.bp-content .bp-toc summary::-webkit-details-marker { display: none; }

.bp-content .bp-toc summary::before {
  content: "";
  width: 7px;
  height: 7px;
  flex: 0 0 auto;
  border-right: 1.5px solid var(--accent);
  border-bottom: 1.5px solid var(--accent);
  transform: rotate(-45deg);
  transition: transform 0.15s ease;
}

.bp-content .bp-toc[open] summary::before { transform: rotate(45deg); }
.bp-content .bp-toc[open] summary { margin-bottom: 0.55rem; }

.bp-content .bp-toc ul {
  margin: 0.2rem 0 0.2rem;
  padding-left: 1.15rem;
  font-size: 0.88em;
  line-height: 1.5;
}

.bp-content .bp-toc li { margin-bottom: 0.12em; }
.bp-content .bp-toc a { text-decoration: none; color: var(--ink-2); }
.bp-content .bp-toc a:hover { color: var(--accent-ink); text-decoration: underline; text-underline-offset: 3px; }

/* ── Reference lists ────────────────────────────────────────────────── */

.bp-content .bp-refs {
  font-size: 0.82em;
  line-height: 1.45;
  color: var(--ink-2);
}

.bp-content .bp-refs p { margin: 0 0 0.4em; }

/* ── Footnotes / misc ───────────────────────────────────────────────── */

.bp-content .footnotes {
  margin-top: 3.5rem;
  padding-top: 1.2rem;
  border-top: 1px solid var(--rule);
  font-size: 0.88em;
  color: var(--ink-2);
}

.bp-content sup { line-height: 1; }

.bp-content .mermaid { text-align: center; margin: 1.8em 0; }

/* ── Related posts / comments ───────────────────────────────────────── */

.bp-related {
  margin-top: 4.5rem;
  padding-top: 1.8rem;
  border-top: 1px solid var(--rule);
}

.bp-related-h {
  margin: 0 0 1rem;
  font-family: var(--mono);
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--ink-3);
}

.bp-related-list { list-style: none; margin: 0; padding: 0; }

.bp-related-list li {
  display: flex;
  align-items: baseline;
  gap: 0.9rem;
  padding: 0.32rem 0;
}

.bp-related-list .bp-item-date {
  flex: 0 0 auto;
  font-family: var(--mono);
  font-size: 0.72rem;
  color: var(--ink-3);
}

.bp-related-list a {
  color: var(--ink);
  font-weight: 500;
  text-decoration: none;
}

.bp-related-list a:hover { color: var(--accent-ink); text-decoration: underline; text-underline-offset: 3px; }

.bp-comments { margin-top: 3.5rem; }

.bp-comments .v { font-family: var(--sans) !important; }
.bp-comments .v .vwrap { border: 1px solid var(--rule); border-radius: 8px; background: var(--panel); }
.bp-comments .v .vbtn { border: 1px solid var(--accent); color: var(--accent-ink); }
.bp-comments .v .vbtn:hover { background: var(--accent-tint); }
.bp-comments .v .vcount { font-family: var(--mono); font-size: 0.85rem; color: var(--ink-2); }

/* ── Listing pages (/blogs/, /archives/) ────────────────────────────── */

.bp-list-head { margin-bottom: 1.2rem; }

.bp-list-sub {
  margin: 0;
  color: var(--ink-2);
}

.bp-list-sub a { color: var(--accent-ink); text-decoration: none; }
.bp-list-sub a:hover { text-decoration: underline; text-underline-offset: 3px; }

.bp-year {
  margin: 2.6rem 0 0.6rem;
  font-family: var(--mono);
  font-size: 0.78rem;
  font-weight: 600;
  letter-spacing: 0.14em;
  color: var(--ink-3);
}

.bp-list { display: block; }

.bp-item {
  display: flex;
  align-items: baseline;
  gap: 1rem;
  padding: 0.42rem 0;
  text-decoration: none;
  border-bottom: 1px solid var(--rule-soft);
}

.bp-item:last-child { border-bottom: 0; }

.bp-item-date {
  flex: 0 0 4.1rem;
  font-family: var(--mono);
  font-size: 0.74rem;
  color: var(--ink-3);
  white-space: nowrap;
}

.bp-item-title {
  color: var(--ink);
  font-weight: 500;
  line-height: 1.45;
}

.bp-item:hover .bp-item-title { color: var(--accent-ink); }

.bp-item-tag {
  margin-left: auto;
  font-family: var(--mono);
  font-size: 0.68rem;
  color: var(--ink-3);
  white-space: nowrap;
}

.bp-item-tag ~ .bp-item-tag { margin-left: 0.5rem; }

/* ── Footer ─────────────────────────────────────────────────────────── */

.bp-footer {
  margin-top: 6rem;
  border-top: 1px solid var(--rule);
}

.bp-footer-inner {
  max-width: var(--col);
  margin: 0 auto;
  padding: 1.6rem 1.4rem 2.4rem;
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 0.5rem 1.5rem;
  font-family: var(--mono);
  font-size: 0.7rem;
  letter-spacing: 0.05em;
  color: var(--ink-3);
}

.bp-footer a { color: inherit; text-decoration: none; }
.bp-footer a:hover { color: var(--accent-ink); }

/* ── Responsive ─────────────────────────────────────────────────────── */

@media (max-width: 640px) {
  body { font-size: 16px; }
  .bp-main { padding-top: 2.2rem; }
  .bp-header-inner { padding: 0.75rem 1.1rem; }
  .bp-main, .bp-footer-inner { padding-left: 1.1rem; padding-right: 1.1rem; }
  .bp-item-tag { display: none; }
  .bp-item-date { flex-basis: 3.6rem; }
}

/* ==========================================================================
   Post figures (.cc-fig): animated SVG/CSS diagrams — shared across posts
   ========================================================================== */

.cc-fig{margin:28px 0;border:1px solid #E6E2D6;background:#fff;padding:18px 16px 14px}
.cc-fig svg{display:block;width:100%;height:auto}
.cc-fig figcaption{margin-top:14px;padding-top:10px;border-top:1px solid #EBE7DB;font-family:var(--sans);font-size:13px;line-height:1.55;color:#6B675F}
.cc-fig .cc-fno{color:#C0552B;font-family:var(--mono);font-size:10.5px;font-weight:600;letter-spacing:.1em;text-transform:uppercase;margin-right:6px}
.cc-fig .cc-edge{stroke:#A29C8C;stroke-width:1.3;fill:none}
.cc-fig .cc-green{stroke:#0E7568}
.cc-fig .cc-amber{stroke:#A16207}
.cc-fig .cc-mag{stroke:#C0552B}
.cc-fig .cc-dashmove{stroke-dasharray:3 5;animation:ccDash .8s linear infinite}
@keyframes ccDash{to{stroke-dashoffset:-8}}
.cc-fig .cc-ntitle{font:600 12px var(--mono);letter-spacing:.05em;fill:#201F1B}
.cc-fig .cc-nsub{font:10.5px var(--sans);fill:#6B675F}
.cc-fig .cc-elab{font:600 9.5px var(--mono);letter-spacing:.08em;fill:#8C877B}
.cc-fig .cc-elab2{font:italic 9.5px var(--sans);fill:#8C877B}
.cc-fig .cc-note{font:italic 11px var(--sans);fill:#8C877B}
.cc-fig .cc-green-t{fill:#0E7568}
.cc-fig .cc-amber-t{fill:#A16207}
.cc-fig .cc-mag-t{fill:#C0552B}
.cc-fig .cc-blue-t{fill:#4C63B6}
.cc-fig .cc-hole{animation:ccHole 2.2s ease-in-out infinite}
@keyframes ccHole{0%,100%{opacity:.25}50%{opacity:1}}
.cc-fig .cc-st{animation:ccStation 7.8s ease-in-out infinite;animation-delay:calc(var(--st)*1.3s)}
@keyframes ccStation{0%,16.7%,100%{stroke-width:1.5}5%{stroke-width:3.2}}
.cc-fig .cc-zoneflicker{animation:ccFlicker 3.6s ease-in-out infinite}
@keyframes ccFlicker{0%,100%{opacity:.55}42%{opacity:.3}55%{opacity:.46}68%{opacity:.33}}
.cc-fig .cc-beat{animation:ccBeat 4.4s ease-in-out infinite;animation-delay:calc(var(--bt)*2.2s)}
@keyframes ccBeat{0%,18%,100%{stroke-width:1.5}6%{stroke-width:3.2}}
.cc-ladder{display:flex;flex-direction:column;gap:7px}
.cc-rung{margin-left:calc(var(--i)*5.5%);border:1px solid #E6E2D6;border-left:3px solid var(--rc);background:#F7F5EE;padding:8px 12px 9px;animation:ccRung 9s infinite;animation-delay:calc(var(--i)*1.5s)}
.cc-rtop{display:flex;align-items:baseline;gap:10px;flex-wrap:wrap}
.cc-rno{font:600 10.5px var(--mono);letter-spacing:.06em;color:var(--rc)}
.cc-rname{font-family:var(--sans);font-size:14px;font-weight:700;color:#201F1B}
.cc-rsub{margin-top:3px;font-size:12.5px;line-height:1.5;color:#6B675F}
.cc-rsub .cc-rk{font:600 9px var(--mono);letter-spacing:.08em;text-transform:uppercase;color:var(--rc);margin-right:5px}
.cc-rsub .cc-rsep{margin:0 8px;color:#C9C4B6}
.cc-rcost{margin-top:7px;height:3px;background:#ECE8DC}
.cc-rcost i{display:block;height:100%;width:var(--w);background:var(--rc)}
.cc-ladleg{margin-top:12px;font:10.5px var(--mono);letter-spacing:.05em;color:#8C877B}
@keyframes ccRung{0%,16.6%,100%{transform:none;box-shadow:none}5%{transform:translateX(4px);box-shadow:0 1px 10px rgba(0,0,0,.09)}}
.cc-tablewrap{overflow-x:auto}
.cc-tablewrap table{font-size:14px}
@media (max-width:600px){.cc-fig{padding:12px 10px 10px}}
@media (prefers-reduced-motion:reduce){.cc-fig .cc-dot{display:none}.cc-fig *{animation:none !important}}