/* ============================================================
   LAYOUT
   Page grid, sidebar, main content, responsive breakpoints
   ============================================================ */

/* ─── Reset & Base ─── */
*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-size: 16px;
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-family);
  font-size: var(--font-size-base);
  font-weight: var(--font-weight-normal);
  line-height: var(--line-height-normal);
  color: var(--text-primary);
  background: var(--bg-primary);
  min-height: 100vh;
  overflow-x: hidden;
  transition: background var(--transition-normal), color var(--transition-normal);
}

/* ─── Global Focus Indicator ─── */
button:focus-visible,
a:focus-visible,
input:focus-visible,
[tabindex]:focus-visible {
  outline: 3px solid var(--border-focus);
  outline-offset: 2px;
}

/* ─── App Shell ─── */
.app-shell {
  display: flex;
  min-height: 100vh;
}

/* ─── Sidebar ─── */
.sidebar {
  position: fixed;
  top: 0;
  left: 0;
  width: var(--sidebar-width);
  height: 100vh;
  height: 100dvh;
  background: var(--bg-sidebar);
  border-right: 1px solid var(--border-color);
  display: flex;
  flex-direction: column;
  z-index: 300;
  transition: transform var(--transition-slow), box-shadow var(--transition-normal);
  overflow: hidden;
}

.sidebar-header {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  padding: 0 var(--space-lg);
  border-bottom: 1px solid var(--border-color);
  height: var(--header-height);
  flex-shrink: 0;
}

.sidebar-logo {
  width: 36px;
  height: 36px;
  flex-shrink: 0;
}

.sidebar-title {
  font-size: var(--font-size-md);
  font-weight: var(--font-weight-bold);
  color: var(--text-primary);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.sidebar-subtitle {
  font-size: var(--font-size-xs);
  color: var(--text-tertiary);
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.sidebar-nav {
  flex: 1;
  overflow-y: auto;
  padding: var(--space-sm) 0;
  scrollbar-width: thin;
  scrollbar-color: var(--border-color) transparent;
}

.sidebar-nav::-webkit-scrollbar {
  width: 4px;
}

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

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

.sidebar-footer {
  padding: var(--space-md) var(--space-lg);
  border-top: 1px solid var(--border-color);
  flex-shrink: 0;
}

/* ─── Main Content Area ─── */
.main-content {
  flex: 1;
  margin-left: var(--sidebar-width);
  min-height: 100vh;
  transition: margin-left var(--transition-slow);
}

/* ─── Top Header Bar ─── */
.top-bar {
  position: sticky;
  top: 0;
  display: flex;
  align-items: center;
  gap: var(--space-md);
  padding: 0 var(--content-padding);
  height: var(--header-height);
  background: var(--bg-tertiary);
  border-bottom: 1px solid var(--border-color);
  z-index: 100;
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
}

[data-theme="light"] .top-bar {
  background: rgba(255, 255, 255, 0.85);
}

[data-theme="dark"] .top-bar {
  background: rgba(26, 26, 46, 0.85);
}

.menu-toggle {
  display: none;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  border: none;
  background: transparent;
  color: var(--text-primary);
  cursor: pointer;
  border-radius: var(--radius-sm);
  transition: background var(--transition-fast);
  flex-shrink: 0;
}

.menu-toggle:hover {
  background: var(--bg-hover);
}

.menu-toggle svg {
  width: 22px;
  height: 22px;
}

/* ─── Content Sections ─── */
.content-body {
  padding: var(--content-padding);
  max-width: calc(var(--max-content-width) + var(--content-padding) * 2);
  margin: 0 auto;
}

.page-hero {
  text-align: center;
  padding: var(--space-3xl) var(--space-xl);
}

.page-hero h1 {
  font-size: var(--font-size-3xl);
  font-weight: var(--font-weight-bold);
  line-height: var(--line-height-tight);
  margin-bottom: var(--space-md);
}

.page-hero p {
  font-size: var(--font-size-lg);
  color: var(--text-secondary);
  max-width: 600px;
  margin: 0 auto;
}

.section-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: var(--space-lg);
  padding: var(--space-lg) 0;
}

.category-list-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: var(--space-md);
}

/* ─── Breadcrumbs ─── */
.breadcrumbs {
  display: flex;
  align-items: center;
  gap: var(--space-xs);
  padding: var(--space-md) 0;
  font-size: var(--font-size-sm);
  color: var(--text-tertiary);
  flex-wrap: wrap;
}

.breadcrumbs a {
  color: var(--text-link);
  text-decoration: none;
  transition: color var(--transition-fast);
}

.breadcrumbs a:hover {
  color: var(--text-link-hover);
}

.breadcrumbs .separator {
  color: var(--text-tertiary);
  margin: 0 2px;
}

/* ─── Mobile Overlay ─── */
.sidebar-overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: var(--bg-overlay);
  z-index: 299;
  opacity: 0;
  transition: opacity var(--transition-normal);
}

.sidebar-overlay.active {
  display: block;
  opacity: 1;
}

/* ─── Responsive ─── */
@media (max-width: 1024px) {
  .sidebar {
    transform: translateX(-100%);
  }

  .sidebar.open {
    transform: translateX(0);
    box-shadow: var(--shadow-lg);
  }

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

  .menu-toggle {
    display: flex;
  }

  .page-hero h1 {
    font-size: var(--font-size-2xl);
  }

  .page-hero {
    padding: var(--space-2xl) var(--space-md);
  }

  .search-shortcut {
    display: none;
  }
}

@media (max-width: 640px) {
  :root {
    --content-padding: var(--space-md);
  }

  .section-grid {
    grid-template-columns: 1fr;
  }

  .category-list-grid {
    grid-template-columns: 1fr;
  }

  .page-hero h1 {
    font-size: var(--font-size-xl);
  }

  .page-hero p {
    font-size: var(--font-size-base);
  }

  .top-bar {
    padding: 0 var(--space-md);
  }
}

/* ─── Utilities ─── */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

.text-center { text-align: center; }
.text-left { text-align: left; }

.mt-sm { margin-top: var(--space-sm); }
.mt-md { margin-top: var(--space-md); }
.mt-lg { margin-top: var(--space-lg); }
.mt-xl { margin-top: var(--space-xl); }
.mb-sm { margin-bottom: var(--space-sm); }
.mb-md { margin-bottom: var(--space-md); }
.mb-lg { margin-bottom: var(--space-lg); }
.mb-xl { margin-bottom: var(--space-xl); }