.article-shell {
  width: min(100%, 1200px);
  margin-inline: auto;
}

.article-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 19rem;
  gap: 2rem;
  align-items: start;
}

.article-content {
  min-width: 0;
}

.article-toc {
  position: sticky;
  top: 6.5rem;
  align-self: start;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  overflow: hidden;
}

.article-toc__toggle {
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
  padding: 1rem 1.125rem;
  border: 0;
  background: transparent;
  color: var(--text);
  font: inherit;
  font-weight: 600;
  text-align: left;
  cursor: pointer;
}

.article-toc__toggle span {
  pointer-events: none;
}

.article-toc__toggle::after {
  content: '';
  width: 0.65rem;
  height: 0.65rem;
  border-right: 2px solid var(--accent, var(--text));
  border-bottom: 2px solid var(--accent, var(--text));
  transform: rotate(45deg);
  transition: transform 0.2s ease;
  flex-shrink: 0;
  margin-top: -0.2rem;
}

.article-toc.is-collapsed .article-toc__toggle::after {
  transform: rotate(-45deg);
  margin-top: 0;
}

.article-toc__nav {
  border-top: 1px solid var(--border);
  padding: 0.5rem 0;
  max-height: min(70vh, 40rem);
  overflow: auto;
  scrollbar-width: thin;
  scroll-behavior: smooth;
}

.article-toc.is-collapsed .article-toc__nav {
  display: none;
}

.article-toc__list {
  list-style: none;
  margin: 0;
  padding: 0;
}

.article-toc__item + .article-toc__item {
  margin-top: 0.15rem;
}

.article-toc__link {
  display: block;
  padding: 0.55rem 1.125rem;
  color: var(--text-muted);
  text-decoration: none;
  line-height: 1.4;
  border-left: 2px solid transparent;
  transition:
    color 0.2s ease,
    background 0.2s ease,
    border-color 0.2s ease;
}

.article-toc__link:hover,
.article-toc__link:focus-visible {
  color: var(--text);
  background: color-mix(in srgb, var(--accent, var(--text)) 8%, transparent);
  border-left-color: var(--accent, var(--text));
  outline: none;
}

.article-toc__link.is-active {
  color: var(--text);
  font-weight: 600;
  background: color-mix(in srgb, var(--accent, var(--text)) 12%, transparent);
  border-left-color: var(--accent, var(--text));
}

.article-toc__item--level-3 .article-toc__link {
  padding-left: 2rem;
  font-size: 0.95em;
}

@media (max-width: 1100px) {
  .article-layout {
    grid-template-columns: 1fr;
  }

  .article-toc {
    position: static;
    order: -1;
  }

  .article-toc__nav {
    max-height: none;
  }
}