/* ==========================================================================
   THE CURRENT — Navigation
   Internal sidebar nav for topic pages, hamburger on mobile.
   Index page uses its own topic-grid layout (no sidebar).
   ========================================================================== */

/* ---- Sidebar (desktop) ---- */
.sidebar-nav {
  width: 16rem;
  flex-shrink: 0;
  position: sticky;
  top: var(--space-lg);
  max-height: calc(100vh - var(--space-2xl));
  overflow-y: auto;
  padding-right: var(--space-lg);
  align-self: flex-start;
}

/* Scrollbar styling */
.sidebar-nav::-webkit-scrollbar {
  width: 4px;
}

.sidebar-nav::-webkit-scrollbar-track {
  background: transparent;
}

.sidebar-nav::-webkit-scrollbar-thumb {
  background-color: var(--border);
  border-radius: 2px;
}

/* ---- Nav groups ---- */
.nav-group {
  margin-bottom: var(--space-lg);
}

.nav-group-title {
  font-family: var(--font-body);
  font-size: var(--text-xs);
  font-weight: var(--weight-semibold);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--accent-structure-mid);
  padding-bottom: var(--space-xs);
  border-bottom: 1px solid var(--border);
  margin-bottom: var(--space-sm);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: space-between;
  user-select: none;
}

.nav-group-title .nav-chevron {
  font-size: 0.6rem;
  transition: transform var(--transition-fast);
  color: var(--text-light);
}

.nav-group.is-collapsed .nav-chevron {
  transform: rotate(-90deg);
}

.nav-group.is-collapsed .nav-group-links {
  display: none;
}

/* ---- Nav links ---- */
.nav-group-links {
  list-style: none;
  padding: 0;
  margin: 0;
}

.nav-group-links li {
  margin: 0;
}

.nav-link {
  display: block;
  padding: var(--space-xs) var(--space-sm);
  font-size: var(--text-sm);
  color: var(--text-light);
  text-decoration: none;
  border-radius: var(--border-radius);
  transition: color var(--transition-fast), background-color var(--transition-fast);
  line-height: 1.45;
}

.nav-link:hover {
  color: var(--accent);
  background-color: var(--accent-light);
  text-decoration: none;
}

.nav-link.is-active {
  color: var(--accent);
  background-color: var(--accent-light);
  font-weight: var(--weight-medium);
}

/* ---- Back to index link ---- */
.nav-home-link {
  display: inline-flex;
  align-items: center;
  gap: var(--space-xs);
  font-size: var(--text-xs);
  font-weight: var(--weight-medium);
  color: var(--accent);
  text-decoration: none;
  margin-bottom: var(--space-lg);
  padding: var(--space-xs) 0;
}

.nav-home-link:hover {
  color: var(--accent-hover);
  text-decoration: none;
}

.nav-home-link .nav-arrow {
  font-size: 0.75rem;
}

/* ---- Mobile nav ---- */
.mobile-nav-header {
  display: none;
}

@media (max-width: 1023px) {
  .sidebar-nav {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 80vw;
    max-width: 20rem;
    height: 100vh;
    max-height: 100vh;
    background-color: var(--bg-section);
    z-index: 100;
    padding: var(--space-lg);
    box-shadow: 4px 0 16px rgba(44, 42, 38, 0.1);
    overflow-y: auto;
  }

  .sidebar-nav.is-open {
    display: block;
  }

  .mobile-nav-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: var(--space-lg);
    padding-bottom: var(--space-md);
    border-bottom: 1px solid var(--border);
  }

  .mobile-nav-title {
    font-family: var(--font-display);
    font-size: 1.125rem;
    font-weight: var(--weight-bold);
    color: var(--text);
  }

  .mobile-nav-close {
    background: none;
    border: none;
    font-size: 1.25rem;
    color: var(--text-light);
    cursor: pointer;
    padding: var(--space-xs);
  }

  .nav-overlay {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    background-color: rgba(44, 42, 38, 0.3);
    z-index: 99;
  }

  .nav-overlay.is-visible {
    display: block;
  }
}

/* ---- Hamburger button (shown on mobile, on topic pages only) ---- */
.nav-toggle {
  display: none;
  background: none;
  border: 1px solid var(--border);
  border-radius: var(--border-radius);
  padding: var(--space-xs) var(--space-sm);
  cursor: pointer;
  color: var(--text);
  font-size: var(--text-sm);
  font-family: var(--font-body);
  align-items: center;
  gap: var(--space-xs);
}

.nav-toggle .hamburger-icon {
  display: inline-block;
  width: 1rem;
  height: 0.75rem;
  position: relative;
}

.nav-toggle .hamburger-icon span {
  display: block;
  width: 100%;
  height: 1.5px;
  background-color: var(--text);
  position: absolute;
  left: 0;
  transition: transform var(--transition-fast);
}

.nav-toggle .hamburger-icon span:nth-child(1) { top: 0; }
.nav-toggle .hamburger-icon span:nth-child(2) { top: 50%; transform: translateY(-50%); }
.nav-toggle .hamburger-icon span:nth-child(3) { bottom: 0; }

@media (max-width: 1023px) {
  .nav-toggle {
    display: inline-flex;
  }
}

/* ---- Layout adjustment for pages with sidebar ---- */
.page-with-sidebar .main-content {
  max-width: var(--page-max-width);
}

.page-with-sidebar .content-layout {
  display: flex;
  gap: var(--space-xl);
}

.page-with-sidebar .article {
  flex: 1;
  min-width: 0;
  max-width: var(--content-max-width);
  overflow-x: hidden;
}

@media (max-width: 1023px) {
  .page-with-sidebar .content-layout {
    flex-direction: column;
  }
}