/* === Reset === */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

/* === Palette === */
:root {
  --bg:       #0d1117;
  --bg-alt:   #161b22;
  --fg:       #c9d1d9;
  --fg-dim:   #8b949e;
  --accent:   #58a6ff;
  --green:    #3fb950;
  --border:   #30363d;
  --code-bg:  #1c2128;
  --max-w:    720px;
  --mono:     "JetBrains Mono", "Fira Code", "Cascadia Code", "SF Mono", Consolas, monospace;
  --sans:     -apple-system, BlinkMacSystemFont, "Segoe UI", Helvetica, Arial, sans-serif;
}

/* === Base === */
html { font-size: 16px; }
body {
  font-family: var(--sans);
  background: var(--bg);
  color: var(--fg);
  line-height: 1.7;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* === Layout === */
header { border-bottom: 1px solid var(--border); padding: 1.25rem 1.5rem; }
nav { max-width: var(--max-w); margin: 0 auto; }
main { max-width: var(--max-w); margin: 0 auto; padding: 2rem 1.5rem; flex: 1; width: 100%; }
footer {
  border-top: 1px solid var(--border);
  padding: 1.5rem;
  text-align: center;
  color: var(--fg-dim);
  font-size: 0.85rem;
}

/* === Nav === */
.site-name {
  font-family: var(--mono);
  font-size: 1.4rem;
  color: var(--green);
  text-decoration: none;
  font-weight: 600;
  letter-spacing: 0.04em;
}
.site-name:hover { color: var(--accent); }

/* === Typography === */
h1, h2, h3, h4 {
  font-family: var(--mono);
  font-weight: 600;
  color: #e6edf3;
  line-height: 1.3;
}
h1 { font-size: 1.75rem; margin: 0 0 0.5rem; }
h2 { font-size: 1.25rem; margin: 2rem 0 0.75rem; padding-bottom: 0.3rem; border-bottom: 1px solid var(--border); }
h3 { font-size: 1.05rem; margin: 1.5rem 0 0.5rem; }
p { margin: 0 0 1rem; }
strong { color: #e6edf3; }
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }
hr { border: none; border-top: 1px solid var(--border); margin: 2rem 0; }

/* === Post header === */
.post-header { margin-bottom: 2rem; padding: 0; border-bottom: none; }
.post-header time {
  font-family: var(--mono);
  font-size: 0.85rem;
  color: var(--fg-dim);
}
.post-byline {
  font-family: var(--mono);
  font-size: 0.85rem;
  color: var(--fg-dim);
}

/* === Lists === */
ul, ol { margin: 0 0 1rem; padding-left: 1.5rem; }
li { margin-bottom: 0.35rem; }
li > ul, li > ol { margin-bottom: 0; }

/* === Blockquotes === */
blockquote {
  border-left: 3px solid var(--accent);
  padding: 0.5rem 1rem;
  margin: 0 0 1rem;
  background: var(--bg-alt);
  border-radius: 0 4px 4px 0;
  color: var(--fg-dim);
}
blockquote p:last-child { margin-bottom: 0; }

/* === Inline code === */
code {
  font-family: var(--mono);
  font-size: 0.88em;
  background: var(--code-bg);
  padding: 0.15em 0.35em;
  border-radius: 3px;
  border: 1px solid var(--border);
}

/* === Code blocks === */
pre.hljs {
  background: var(--code-bg);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 1rem;
  margin: 0 0 1rem;
  overflow-x: auto;
  position: relative;
}
pre.hljs code {
  background: none;
  border: none;
  padding: 0;
  font-size: 0.85rem;
  line-height: 1.5;
}

/* Copy button */
.copy-btn {
  position: absolute;
  top: 0.5rem;
  right: 0.5rem;
  background: var(--bg-alt);
  border: 1px solid var(--border);
  border-radius: 4px;
  color: var(--fg-dim);
  font-size: 0;
  padding: 0.35rem;
  cursor: pointer;
  opacity: 0;
  transition: opacity 0.15s;
}
pre.hljs:hover .copy-btn { opacity: 1; }
.copy-btn:hover { color: var(--fg); border-color: var(--fg-dim); }
.copy-btn.copied { color: var(--green); border-color: var(--green); }

/* === Formulas (Computer Modern) === */
@font-face {
  font-family: "CMU Serif";
  src: url("/fonts/cmu-serif-500-roman.woff2") format("woff2");
  font-weight: normal;
  font-style: normal;
  font-display: swap;
}
@font-face {
  font-family: "CMU Serif";
  src: url("/fonts/cmu-serif-500-italic.woff2") format("woff2");
  font-weight: normal;
  font-style: italic;
  font-display: swap;
}
.formula {
  font-family: "CMU Serif", "Latin Modern Roman", "Times New Roman", serif;
  font-size: 1.2rem;
  text-align: center;
  padding: 1.25rem 1rem;
  margin: 1rem 0;
  background: var(--bg-alt);
  border-radius: 6px;
  border: 1px solid var(--border);
  color: #e6edf3;
}
.formula var { font-style: italic; }
.formula sub { font-size: 0.7em; }

/* === 2026 update annotations === */
.update-banner {
  border: 1px solid var(--green);
  border-left: 3px solid var(--green);
  background: var(--bg-alt);
  border-radius: 0 4px 4px 0;
  padding: 0.75rem 1rem;
  margin: 1.5rem 0;
  font-size: 0.9rem;
  color: var(--fg-dim);
}
.update-banner strong { color: var(--green); }
.update-inline {
  color: var(--green);
  font-style: italic;
}

/* === Images === */
img {
  max-width: 100%;
  height: auto;
  border-radius: 6px;
  border: 1px solid var(--border);
  margin: 1rem 0;
}

/* === Tables === */
table {
  width: 100%;
  border-collapse: collapse;
  margin: 0 0 1rem;
  font-size: 0.9rem;
}
th, td {
  padding: 0.5rem 0.75rem;
  border: 1px solid var(--border);
  text-align: left;
}
th { background: var(--bg-alt); font-weight: 600; color: #e6edf3; }

/* === Index page === */
main > h1 { font-size: 1.4rem; }
main > h2 { color: var(--fg); }
.tagline {
  font-size: 1.05rem;
  color: var(--fg-dim);
  margin-bottom: 0.5rem;
}
.links {
  font-family: var(--mono);
  font-size: 0.85rem;
  margin-bottom: 2.5rem;
}
.links a { margin-right: 1.5rem; }
.post-list { list-style: none; padding: 0; }
.post-list li {
  margin-bottom: 1.25rem;
  padding-bottom: 1.25rem;
  border-bottom: 1px solid var(--border);
}
.post-list li:last-child { border-bottom: none; }
.post-list a {
  font-family: var(--mono);
  font-size: 1.05rem;
  font-weight: 600;
}
.post-list .post-meta {
  font-size: 0.85rem;
  color: var(--fg-dim);
  margin-top: 0.25rem;
}

.post-private {
  font-size: 0.7rem;
  color: var(--fg-dim);
  opacity: 0.6;
}

/* === Responsive === */
@media (max-width: 600px) {
  h1 { font-size: 1.25rem; }
  main > h1 { font-size: 1.3rem; }
  h2 { font-size: 1.1rem; }
  main { padding: 1.5rem 1rem; }
}