/* ============================================
   EduFace AI — Layout
   Sidebar, Topbar, Main Grid, Responsive
   ============================================ */

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

.app-main {
  flex: 1;
  margin-left: var(--sidebar-width);
  display: flex;
  flex-direction: column;
  min-height: 100vh;
  transition: margin-left var(--transition-base);
}

.app-content {
  flex: 1;
  padding: var(--space-xl);
  margin-top: var(--topbar-height);
}

/* --- Sidebar --- */
.sidebar {
  position: fixed;
  top: 0;
  left: 0;
  width: var(--sidebar-width);
  height: 100vh;
  background: var(--bg-secondary);
  border-right: 1px solid var(--border-glass);
  display: flex;
  flex-direction: column;
  z-index: var(--z-sidebar);
  transition: width var(--transition-base), transform var(--transition-base);
  overflow: hidden;
}

.sidebar-header {
  padding: var(--space-lg) var(--space-lg);
  display: flex;
  align-items: center;
  gap: var(--space-md);
  border-bottom: 1px solid var(--border-glass);
  min-height: 72px;
}

.sidebar-logo {
  width: 40px;
  height: 40px;
  border-radius: var(--radius-md);
  background: var(--gradient-hero);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.25rem;
  flex-shrink: 0;
}

.sidebar-brand {
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

.sidebar-brand-name {
  font-size: var(--font-size-lg);
  font-weight: var(--font-weight-bold);
  color: var(--text-primary);
  white-space: nowrap;
  background: var(--gradient-hero);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.sidebar-brand-sub {
  font-size: var(--font-size-xs);
  color: var(--text-muted);
  white-space: nowrap;
}

.sidebar-nav {
  flex: 1;
  padding: var(--space-md) var(--space-sm);
  overflow-y: auto;
}

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

.sidebar-nav-label {
  font-size: var(--font-size-xs);
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  padding: var(--space-sm) var(--space-md);
  font-weight: var(--font-weight-semibold);
}

.sidebar-nav-item {
  display: flex;
  align-items: center;
  gap: var(--space-md);
  padding: 0.625rem var(--space-md);
  margin: 2px 0;
  border-radius: var(--radius-md);
  color: var(--text-secondary);
  transition: all var(--transition-fast);
  cursor: pointer;
  white-space: nowrap;
  position: relative;
}

.sidebar-nav-item:hover {
  color: var(--text-primary);
  background: rgba(148, 163, 184, 0.08);
}

.sidebar-nav-item.active {
  color: var(--accent-teal);
  background: rgba(6, 182, 212, 0.1);
}

.sidebar-nav-item.active::before {
  content: '';
  position: absolute;
  left: 0;
  top: 50%;
  transform: translateY(-50%);
  width: 3px;
  height: 60%;
  background: var(--accent-teal);
  border-radius: 0 3px 3px 0;
}

.sidebar-nav-item .nav-icon {
  font-size: 1.25rem;
  width: 24px;
  height: 24px;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.sidebar-nav-item .nav-label {
  overflow: hidden;
  transition: opacity var(--transition-fast);
}

.sidebar-footer {
  padding: var(--space-md) var(--space-lg);
  border-top: 1px solid var(--border-glass);
  display: flex;
  align-items: center;
  gap: var(--space-md);
}

.sidebar-footer-avatar {
  width: 36px;
  height: 36px;
  border-radius: var(--radius-full);
  background: var(--gradient-purple);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: var(--font-weight-semibold);
  font-size: var(--font-size-sm);
  flex-shrink: 0;
}

.sidebar-footer-info {
  overflow: hidden;
}

.sidebar-footer-name {
  font-size: var(--font-size-sm);
  font-weight: var(--font-weight-medium);
  color: var(--text-primary);
  white-space: nowrap;
}

.sidebar-footer-role {
  font-size: var(--font-size-xs);
  color: var(--text-muted);
}

/* --- Topbar --- */
.topbar {
  position: fixed;
  top: 0;
  left: var(--sidebar-width);
  right: 0;
  height: var(--topbar-height);
  background: rgba(255, 255, 255, 0.85);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--border-glass);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 var(--space-xl);
  z-index: var(--z-topbar);
  transition: left var(--transition-base);
}

.topbar-left {
  display: flex;
  align-items: center;
  gap: var(--space-md);
}

.topbar-hamburger {
  display: none;
  padding: var(--space-sm);
  border-radius: var(--radius-sm);
  color: var(--text-secondary);
  cursor: pointer;
  transition: all var(--transition-fast);
}
.topbar-hamburger:hover {
  color: var(--text-primary);
  background: rgba(148, 163, 184, 0.08);
}

.topbar-title {
  font-size: var(--font-size-lg);
  font-weight: var(--font-weight-semibold);
}

.topbar-right {
  display: flex;
  align-items: center;
  gap: var(--space-lg);
}

.topbar-search {
  position: relative;
}

.topbar-search input {
  width: 240px;
  padding-left: 2.25rem;
  background: var(--bg-glass);
  border: 1px solid var(--border-glass);
  border-radius: var(--radius-lg);
  font-size: var(--font-size-sm);
}

.topbar-search .search-icon {
  position: absolute;
  left: 0.75rem;
  top: 50%;
  transform: translateY(-50%);
  color: var(--text-muted);
  font-size: 1.1rem;
}

.topbar-clock {
  font-family: var(--font-mono);
  font-size: var(--font-size-sm);
  color: var(--text-secondary);
  background: var(--bg-glass);
  padding: 0.375rem 0.75rem;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-glass);
  min-width: 80px;
  text-align: center;
}

.topbar-date {
  font-size: var(--font-size-xs);
  color: var(--text-muted);
  display: none;
}

/* --- Page Container --- */
.page {
  animation: fadeIn 0.3s ease forwards;
}

.page-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: var(--space-xl);
  flex-wrap: wrap;
  gap: var(--space-md);
}

.page-header-left h2 {
  font-size: var(--font-size-2xl);
  margin-bottom: var(--space-xs);
}

.page-header-left p {
  color: var(--text-secondary);
  font-size: var(--font-size-sm);
}

/* --- Overlay (mobile sidebar) --- */
.sidebar-overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: var(--bg-overlay);
  z-index: calc(var(--z-sidebar) - 1);
  opacity: 0;
  transition: opacity var(--transition-base);
}

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

/* --- Responsive --- */
@media (max-width: 1024px) {
  .sidebar {
    width: var(--sidebar-collapsed);
  }
  .sidebar .nav-label,
  .sidebar .sidebar-brand,
  .sidebar .sidebar-footer-info,
  .sidebar .sidebar-nav-label {
    display: none;
  }
  .sidebar-header {
    justify-content: center;
    padding: var(--space-lg) var(--space-sm);
  }
  .sidebar-nav-item {
    justify-content: center;
    padding: 0.625rem;
  }
  .sidebar-nav-item.active::before {
    display: none;
  }
  .sidebar-footer {
    justify-content: center;
    padding: var(--space-md) var(--space-sm);
  }
  .app-main {
    margin-left: var(--sidebar-collapsed);
  }
  .topbar {
    left: var(--sidebar-collapsed);
  }
  .grid-4 {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 768px) {
  .sidebar {
    width: var(--sidebar-width);
    transform: translateX(-100%);
  }
  .sidebar.open {
    transform: translateX(0);
  }
  .sidebar.open .nav-label,
  .sidebar.open .sidebar-brand,
  .sidebar.open .sidebar-footer-info,
  .sidebar.open .sidebar-nav-label {
    display: block;
  }
  .sidebar.open .sidebar-nav-item {
    justify-content: flex-start;
    padding: 0.625rem var(--space-md);
  }
  .sidebar.open .sidebar-header {
    justify-content: flex-start;
    padding: var(--space-lg);
  }
  .sidebar.open .sidebar-footer {
    justify-content: flex-start;
    padding: var(--space-md) var(--space-lg);
  }
  .app-main {
    margin-left: 0;
  }
  .topbar {
    left: 0;
  }
  .topbar-hamburger {
    display: flex;
  }
  .topbar-search {
    display: none;
  }
  .topbar-date {
    display: none;
  }
  .app-content {
    padding: var(--space-md);
  }
  .grid-4 {
    grid-template-columns: 1fr 1fr;
  }
  .grid-3 {
    grid-template-columns: 1fr;
  }
  .grid-2 {
    grid-template-columns: 1fr;
  }
  .page-header {
    flex-direction: column;
    align-items: flex-start;
  }
}

@media (max-width: 480px) {
  .grid-4 {
    grid-template-columns: 1fr;
  }
}