/* Blog-style research layout: hideable sidebar on the left, content and contents rail on the right. */
.layout {
  display: flex;
  min-height: calc(100vh - 60px);
}

.layout .sidebar {
  position: sticky;
  top: 60px;
  align-self: flex-start;
  display: flex;
  flex-direction: column;
  width: 320px;
  min-width: 320px;
  max-height: none;
  height: calc(100vh - 60px);
  padding: 0;
  overflow: hidden;
  background: var(--panel);
  border-right: 1px solid var(--border);
}

.layout.sidebar-collapsed .sidebar {
  display: none;
}

.layout .content {
  flex: 1;
  min-width: 0;
}

.sidebar-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 24px 20px 16px;
  border-bottom: 1px solid var(--border);
}

.sidebar-title {
  color: var(--secondary);
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 1.5px;
  text-transform: uppercase;
}

.post-count {
  color: var(--secondary);
  font-family: var(--font-mono);
  font-size: 12px;
}

.sidebar-search {
  position: relative;
  padding: 12px 20px;
  border-bottom: 1px solid var(--border);
}

.sidebar-search .search {
  margin: 0;
  padding: 10px 12px 10px 36px;
  background: var(--panel-2);
  border: 1px solid var(--border);
  font-size: 14px;
}

.search-icon {
  position: absolute;
  left: 32px;
  top: 50%;
  width: 14px;
  height: 14px;
  color: var(--secondary);
  transform: translateY(-50%);
  pointer-events: none;
}

.layout .filters {
  gap: 6px;
  margin: 0;
  padding: 12px 20px;
  border-bottom: 1px solid var(--border);
}

.layout .filters button {
  padding: 4px 10px;
  background: var(--panel-2);
  border: 1px solid var(--border);
  color: var(--secondary);
  font-family: var(--font-ui);
  font-size: 11px;
  font-weight: 500;
  letter-spacing: 0.5px;
  text-transform: uppercase;
}

.layout .filters button:hover {
  border-color: var(--secondary);
  color: var(--text);
}

.layout .filters button[aria-pressed="true"] {
  background: var(--accent);
  border-color: var(--accent);
  color: var(--on-accent);
}

.sidebar-posts {
  flex: 1;
  padding: 8px 0;
  overflow-y: auto;
}

.sidebar-post-item {
  display: block;
  padding: 14px 20px;
  border-left: 2px solid transparent;
  color: var(--text);
  text-decoration: none;
}

.sidebar-post-item:hover {
  background: var(--hover);
  border-left-color: var(--border-strong);
  text-decoration: none;
  color: var(--text);
}

.sidebar-post-item[aria-current="page"] {
  background: var(--panel-2);
  border-left-color: var(--accent);
}

.sidebar-post-meta {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 4px;
}

.sidebar-post-date {
  color: var(--secondary);
  font-family: var(--font-mono);
  font-size: 12px;
}

.sidebar-post-tag {
  padding: 1px 6px;
  border-radius: var(--radius-control);
  background: var(--accent);
  color: var(--on-accent);
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.5px;
  text-transform: uppercase;
}

.sidebar-post-title {
  display: block;
  color: var(--text);
  font-size: 15px;
  font-weight: 500;
  line-height: 1.4;
}

.sidebar-post-item:hover .sidebar-post-title {
  color: var(--accent);
}

.sidebar-post-excerpt {
  display: -webkit-box;
  margin-top: 4px;
  color: var(--secondary);
  font-size: 12px;
  line-height: 1.5;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.sidebar-toggle,
.to-top {
  position: fixed;
  left: 332px;
  z-index: 100;
  display: flex;
  align-items: center;
  gap: 6px;
  height: 36px;
  padding: 0 12px;
  background: var(--panel-2);
  border: 1px solid var(--border);
  border-radius: var(--radius-control);
  color: var(--secondary);
  font-family: var(--font-ui);
  font-size: 13px;
  font-weight: 500;
  letter-spacing: 0;
  text-transform: none;
  cursor: pointer;
  transition: color var(--duration) ease, background var(--duration) ease;
}

.sidebar-toggle {
  top: 76px;
}

.to-top {
  top: 120px;
}

.layout.sidebar-collapsed .sidebar-toggle,
.layout.sidebar-collapsed .to-top {
  left: 16px;
}

.sidebar-toggle:hover,
.to-top:hover {
  background: var(--hover);
  color: var(--accent);
}

.sidebar-toggle svg,
.to-top svg {
  width: 14px;
  height: 14px;
}

.layout.sidebar-collapsed .sidebar-toggle svg {
  transform: rotate(180deg);
}

.to-top[hidden] {
  display: none;
}

/* Index content */
.blog-header {
  padding: 60px 60px 40px;
}

.blog-header .page-title {
  margin-bottom: 12px;
}

.blog-grid {
  padding: 0 60px 60px;
}

.layout .index-grid {
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.blog-foot {
  padding: 0 60px 60px;
}

/* Post view */
.post-view {
  width: 100%;
  max-width: 840px;
  margin: 0 auto;
  padding: 60px 40px 80px;
}

.layout.sidebar-collapsed .post-view {
  max-width: clamp(840px, 68vw, 1040px);
}

.post-toc {
  position: fixed;
  top: 60px;
  right: 24px;
  z-index: 50;
  display: none;
  flex-direction: column;
  align-items: flex-end;
  justify-content: center;
  gap: 6px;
  height: calc(100vh - 60px);
  max-width: 180px;
  padding: 48px 0;
  overflow: hidden;
}

.post-toc a {
  display: block;
  max-width: 180px;
  padding: 4px 0;
  overflow: hidden;
  color: var(--secondary);
  font-size: 12px;
  font-weight: 500;
  line-height: 1.3;
  text-align: right;
  text-decoration: none;
  text-overflow: ellipsis;
  white-space: nowrap;
  transition: color var(--duration) ease;
}

.post-toc a:hover {
  color: var(--text);
}

.post-toc a.active {
  color: var(--accent);
  font-weight: 600;
}

@media (min-width: 1301px) {
  .post-toc {
    display: flex;
  }

  .layout:not(.sidebar-collapsed) .post-view {
    padding-right: 204px;
    max-width: 1044px;
  }
}

.scroll-progress {
  position: fixed;
  top: 0;
  left: 0;
  z-index: 1001;
  width: 0;
  height: 2px;
  background: var(--accent);
}

@media (max-width: 900px) {
  .layout {
    display: block;
  }

  .layout .sidebar {
    position: static;
    width: auto;
    min-width: 0;
    height: auto;
    max-height: 420px;
    border-right: 0;
    border-bottom: 1px solid var(--border);
  }

  .sidebar-toggle,
  .to-top {
    display: none;
  }

  .blog-header {
    padding: 40px 20px 24px;
  }

  .blog-grid,
  .blog-foot {
    padding-left: 20px;
    padding-right: 20px;
  }

  .layout .index-grid {
    grid-template-columns: 1fr;
  }

  .post-view {
    padding: 40px 20px 60px;
  }
}

/* Tighter tag chips, bounded tag area, and mobile sidebar rules. */
.layout .filters {
  max-height: 150px;
  overflow-y: auto;
}

.layout .filters button {
  padding: 3px 8px;
  line-height: 1.3;
}

@media (max-width: 900px) {
  .layout.sidebar-collapsed .sidebar {
    display: flex;
  }

  .layout .sidebar {
    max-height: none;
  }

  .layout .sidebar-posts {
    display: none;
  }

  .layout:has(.post-view) .sidebar {
    display: none;
  }

  .layout .filters {
    max-height: 132px;
  }
}

@media (min-width: 901px) {
  .layout .index-grid {
    grid-template-columns: repeat(auto-fill, minmax(290px, 1fr));
  }

  .layout .blog-card-image {
    aspect-ratio: 16 / 9;
  }
}