/* --- Reset-ish --- */
* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
body {
  font-family: system-ui, -apple-system, Segoe UI, Roboto, Ubuntu, Cantarell, "Helvetica Neue", Arial, "Noto Sans", "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol", "Noto Color Emoji";
  line-height: 1.65;
  color: #0f172a;
  background: #f8fafc;
}
a { color: #2563eb; text-decoration: none; }
a:hover { text-decoration: underline; }

.container { max-width: 920px; margin: 0 auto; padding: 2rem 1.25rem; }

/* Header */
.site-header {
  background: linear-gradient(135deg, #111827, #1f2937 60%, #374151);
  color: white;
  position: relative;
  overflow: hidden;
}
.site-header .container { padding-top: 4rem; padding-bottom: 4rem; }
.site-title { font-size: clamp(2rem, 4vw, 3rem); margin: 0 0 0.25rem 0; }
.site-subtitle { opacity: 0.9; margin: 0.25rem 0 1rem 0; font-size: 1.1rem; }
.hero {
  position: relative;
  border-radius: 12px;
  overflow: hidden;
  margin-top: 1.5rem;
  box-shadow: 0 10px 30px rgba(0,0,0,0.25);
}
.hero img { width: 100%; display: block; }
.hero .overlay {
  position: absolute; inset: 0;
  background: linear-gradient(180deg, rgba(0,0,0,0.35), rgba(0,0,0,0.55));
}

/* TOC */
.toc {
  background: #ffffff;
  border: 1px solid #e2e8f0;
  border-radius: 12px;
  padding: 1rem 1.25rem;
  margin: -2rem auto 2rem auto;
  box-shadow: 0 6px 16px rgba(0,0,0,0.05);
}
.toc h2 { margin: 0 0 0.5rem 0; font-size: 1.1rem; }
.toc ul { list-style: none; padding: 0; margin: 0; columns: 1; }
.toc li { margin: 0.35rem 0; }
@media (min-width: 700px) {
  .toc ul { columns: 2; }
}

/* Content */
main.article {
  background: #ffffff;
  border-radius: 12px;
  border: 1px solid #e2e8f0;
  box-shadow: 0 10px 25px rgba(2,6,23,0.05);
  padding: 2rem;
}
.article h1, .article h2, .article h3 {
  line-height: 1.25;
  scroll-margin-top: 80px;
}
.article h1 { font-size: 2rem; margin-top: 0; }
.article h2 { font-size: 1.6rem; margin-top: 2rem; }
.article h3 { font-size: 1.25rem; margin-top: 1.75rem; color: #111827; }
.article p { margin: 0.75rem 0 0.75rem; }
.article ul { padding-left: 1.1rem; }
.article li { margin: 0.4rem 0; }

/* Footer */
.site-footer {
  color: #475569;
  font-size: 0.95rem;
}

/* Callouts */
.callout {
  background: #f1f5f9;
  border-left: 4px solid #2563eb;
  padding: 0.75rem 1rem;
  border-radius: 6px;
  margin: 1rem 0;
}