/* Page layout: sidebar + main content */
.page-layout {
  display: flex;
  min-height: 100vh;
}

/* --- Category Sidebar (homepage) --- */
.category-sidebar {
  position: fixed;
  top: 0;
  left: 0;
  width: 260px;
  height: 100vh;
  overflow-y: auto;
  padding: var(--space-xl) var(--space-lg);
  border-right: 1px solid var(--color-border-light);
  background: var(--color-surface);
}

.site-title {
  font-family: var(--font-heading);
  font-size: var(--font-size-xl);
  font-weight: 700;
  color: var(--color-text);
  margin-bottom: var(--space-xl);
  letter-spacing: var(--letter-spacing-tight);
}

.category-nav {
  font-size: var(--font-size-sm);
}

.nav-group {
  margin-bottom: var(--space-lg);
}

.nav-group__title {
  font-size: var(--font-size-xs);
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: var(--letter-spacing-wide);
  color: var(--color-text-muted);
  margin-bottom: var(--space-sm);
}

.nav-group__list {
  list-style: none;
  padding: 0;
}

.nav-group__item {
  margin-bottom: 2px;
}

.nav-group__link {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.35rem 0.75rem;
  border-radius: var(--radius-sm);
  color: var(--color-text-secondary);
  transition: all var(--transition-fast);
}

.nav-group__link:hover {
  background: var(--color-bg-alt);
  color: var(--color-text);
}

.nav-group__link--active {
  background: var(--color-accent-soft);
  color: var(--color-accent);
  font-weight: 600;
}

.nav-group__count {
  font-size: var(--font-size-xs);
  color: var(--color-text-muted);
}

/* --- TOC Sidebar (post page) --- */
.toc-sidebar {
  position: fixed;
  top: 0;
  left: 0;
  width: 260px;
  height: 100vh;
  overflow-y: auto;
  padding: var(--space-xl) var(--space-lg);
  border-right: 1px solid var(--color-border-light);
  background: var(--color-surface);
}

.back-link {
  display: inline-block;
  font-size: var(--font-size-sm);
  color: var(--color-text-muted);
  margin-bottom: var(--space-lg);
  transition: color var(--transition-fast);
}

.back-link:hover {
  color: var(--color-accent);
}

.toc-title {
  font-size: var(--font-size-xs);
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: var(--letter-spacing-wide);
  color: var(--color-text-muted);
  margin-bottom: var(--space-md);
}

.toc-list {
  list-style: none;
  padding: 0;
}

.toc-list li {
  margin-bottom: 2px;
}

.toc-list a {
  display: block;
  padding: 0.3rem 0.75rem;
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
  border-radius: var(--radius-sm);
  border-left: 2px solid transparent;
  transition: all var(--transition-fast);
}

.toc-list a:hover {
  color: var(--color-text);
  background: var(--color-bg-alt);
}

.toc-list a.active {
  color: var(--color-accent);
  border-left-color: var(--color-accent);
  background: rgba(194, 65, 12, 0.04);
}

.toc-list .toc-level-3 {
  padding-left: 1.5rem;
}

/* --- Main content area --- */
.main-content {
  flex: 1;
  margin-left: 260px;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

.content-wrapper {
  max-width: 48rem;
  margin: 0 auto;
  padding: var(--space-2xl) var(--space-xl);
  flex: 1;
}

.content-wrapper--wide {
  max-width: none;
  width: 60%;
  margin: 0 auto;
  padding: var(--space-2xl) 0;
}

/* --- Post header --- */
.post-header {
  margin-bottom: var(--space-xl);
}

.post-header h1 {
  font-family: var(--font-heading);
  font-size: var(--font-size-2xl);
  font-weight: 700;
  color: var(--color-text);
  letter-spacing: var(--letter-spacing-tight);
  line-height: var(--line-height-tight);
}

/* --- Post navigation (prev/next) --- */
.post-nav {
  display: flex;
  justify-content: space-between;
  gap: var(--space-md);
  margin-top: var(--space-3xl);
  padding-top: var(--space-xl);
  border-top: 1px solid var(--color-border-light);
}

.post-nav__link {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
  padding: var(--space-sm) var(--space-md);
  border-radius: var(--radius-md);
  transition: background var(--transition-fast);
  max-width: 45%;
}

.post-nav__link:hover {
  background: var(--color-bg-alt);
}

.post-nav__link--next {
  text-align: right;
  margin-left: auto;
}

.post-nav__label {
  font-size: var(--font-size-xs);
  color: var(--color-text-muted);
}

.post-nav__title {
  font-size: var(--font-size-sm);
  color: var(--color-accent);
  font-weight: 500;
}

/* --- Category page --- */
.category-header {
  margin-bottom: var(--space-xl);
}

.category-header h2 {
  font-family: var(--font-heading);
  font-size: var(--font-size-2xl);
  font-weight: 700;
  color: var(--color-text);
}

.phase-group {
  margin-bottom: var(--space-xl);
  padding: var(--space-lg);
  background: var(--color-surface);
  border: 1px solid #bfdbfe;
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
}

.phase-group__title {
  font-size: var(--font-size-lg);
  font-weight: 700;
  color: var(--color-text);
  margin-bottom: var(--space-md);
  display: flex;
  align-items: center;
  gap: var(--space-sm);
}

.phase-group__title::before {
  content: '';
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: #60a5fa;
  flex-shrink: 0;
}

.post-list {
  list-style: none;
  padding: 0;
}

.post-list__item {
  margin-bottom: 2px;
}

.post-list__link {
  display: flex;
  align-items: center;
  gap: var(--space-md);
  padding: 0.5rem 0.75rem;
  border-radius: var(--radius-sm);
  color: var(--color-text-secondary);
  transition: all var(--transition-fast);
  font-size: var(--font-size-base);
}

.post-list__link:hover {
  background: var(--color-bg-alt);
  color: var(--color-text);
}

.post-list__order {
  flex: 0 0 2em;
  text-align: right;
  font-size: var(--font-size-sm);
  color: var(--color-text-muted);
}

.post-list__title {
  color: var(--color-accent);
}

/* --- Footer --- */
.site-footer {
  padding: var(--space-xl);
  text-align: center;
  font-size: var(--font-size-xs);
  color: var(--color-text-muted);
  border-top: 1px solid var(--color-border-light);
  margin-top: auto;
}

/* --- Responsive --- */
@media (max-width: 1024px) {
  .category-sidebar,
  .toc-sidebar {
    position: static;
    width: 100%;
    height: auto;
    border-right: none;
    border-bottom: 1px solid var(--color-border-light);
  }

  .page-layout {
    flex-direction: column;
  }

  .main-content {
    margin-left: 0;
  }
}