body {
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

.post-layout {
  display: flex;
  flex: 1;
  max-width: 1100px;
  margin: clamp(1.5rem, 6vw, 2.5rem) auto;
  padding: 0 clamp(1rem, 4vw, 2.5rem);
  gap: 3rem;
  width: 100%;
  align-items: flex-start;
}

/* ── TOC ── */
#toc-sidebar {
  position: sticky;
  top: 1.5rem;
  width: 220px;
  flex-shrink: 0;
  max-height: calc(100vh - 3rem);
  overflow-y: auto;
  scrollbar-width: thin;
  scrollbar-color: var(--border) transparent;
}

#toc-sidebar h2 {
  font-size: 0.65rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--text);
  opacity: 0.6;
  margin: 0 0 0.75rem;
}

#toc-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 2px;
}

#toc-list a {
  display: block;
  padding: 3px 8px;
  font-size: 0.8rem;
  color: var(--text);
  text-decoration: none;
  border-left: 2px solid transparent;
  border-radius: 0 4px 4px 0;
  transition: color 0.15s, border-color 0.15s;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  opacity: 0.7;
}

#toc-list a:hover { opacity: 1; }
#toc-list a.active { color: var(--accent); border-left-color: var(--accent); opacity: 1; }
#toc-list li[data-depth="2"] a { padding-left: 18px; }
#toc-list li[data-depth="3"] a { padding-left: 32px; font-size: 0.76rem; }

/* ── Post content ── */
#post-content {
  flex: 1;
  min-width: 0;
}

.post-meta {
  font-size: 0.85rem;
  color: var(--text);
  opacity: 0.75;
  margin-bottom: 2rem;
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
}

#post-content h1 { font-size: clamp(1.6rem, 4vw, 2.25rem); color: var(--main-text); margin: 0 0 0.5rem; }
#post-content h2 { font-size: 1.4rem; color: var(--main-text); margin: 2.5rem 0 0.75rem; border-bottom: 1px solid var(--border); padding-bottom: 0.35rem; }
#post-content h3 { font-size: 1.1rem; color: var(--main-text); margin: 2rem 0 0.5rem; }
#post-content p  { line-height: 1.75; color: var(--text); margin-bottom: 1.1rem; }

#post-content h1, #post-content h2, #post-content h3 { scroll-margin-top: 1.5rem; }

#post-content a { color: var(--accent); }

#post-content code {
  background: color-mix(in srgb, var(--text) 10%, transparent);
  border-radius: 4px;
  padding: 1px 5px;
  font-size: 0.88em;
  font-family: "JetBrains Mono", "Fira Code", monospace;
}

#post-content pre {
  background: color-mix(in srgb, var(--text) 10%, transparent);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 1.25rem;
  overflow-x: auto;
  margin-bottom: 1.25rem;
}

#post-content pre code { background: none; padding: 0; font-size: 0.875rem; }

#post-content ul, #post-content ol {
  padding-left: 1.5rem;
  margin-bottom: 1rem;
  color: var(--text);
  line-height: 1.8;
}

#post-content blockquote {
  border-left: 3px solid var(--border);
  padding-left: 1rem;
  margin: 1.25rem 0;
  color: var(--text);
  opacity: 0.8;
  font-style: italic;
}

#post-content hr { border: none; border-top: 1px solid var(--border); margin: 2rem 0; }

#post-content table { width: 100%; border-collapse: collapse; margin-bottom: 1.25rem; font-size: 0.9rem; }
#post-content th, #post-content td { padding: 0.5rem 0.75rem; border: 1px solid var(--border); color: var(--text); }
#post-content th { color: var(--main-text); }

/* KaTeX display math */
.katex-display { overflow-x: auto; padding: 0.5rem 0; }

.back-link {
  display: inline-block;
  margin-bottom: 2rem;
  font-size: 0.9rem;
}

@media (max-width: 768px) {
  .post-layout { flex-direction: column; gap: 1.5rem; }
  #toc-sidebar { position: static; width: 100%; max-height: none; border-bottom: 1px solid var(--border); padding-bottom: 1rem; }
}

.post-comments {
  max-width: 1100px;
  margin: 0 auto 3rem;
  padding: 2rem clamp(1rem, 4vw, 2.5rem) 0;
  border-top: 1px solid var(--border);
  width: 100%;
}