/* Header */
.header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--header-height);
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  display: flex;
  align-items: center;
  padding: 0 24px;
  z-index: 100;
  box-shadow: 0 1px 3px rgba(0,0,0,0.05);
}

.header-logo {
  display: flex;
  align-items: center;
  gap: 12px;
  font-weight: 700;
  font-size: 1.125rem;
  color: var(--text-primary);
  text-decoration: none;
}

.header-logo svg {
  width: 32px;
  height: 32px;
  color: var(--primary);
}

.menu-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: 8px;
  margin-right: 12px;
  color: var(--text-secondary);
}

/* Sidebar */
.sidebar {
  position: fixed;
  top: var(--header-height);
  left: 0;
  width: var(--sidebar-width);
  height: calc(100vh - var(--header-height));
  background: var(--surface);
  border-right: 1px solid var(--border);
  overflow-y: auto;
  padding: 24px 0;
  z-index: 50;
  transition: transform var(--transition);
}

.sidebar-section {
  margin-bottom: 8px;
}

.sidebar-section-title {
  padding: 12px 24px 8px;
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-muted);
}

.sidebar-item {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 10px 24px;
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 0.875rem;
  transition: all var(--transition);
  cursor: pointer;
  border-left: 3px solid transparent;
}

.sidebar-item:hover {
  background: var(--border-light);
  color: var(--text-primary);
}

.sidebar-item.active {
  background: var(--primary-light);
  color: var(--primary);
  border-left-color: var(--primary);
  font-weight: 500;
}

.sidebar-item-number {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 24px;
  height: 24px;
  border-radius: 6px;
  background: var(--border-light);
  font-size: 0.75rem;
  font-weight: 600;
  flex-shrink: 0;
}

.sidebar-item.active .sidebar-item-number {
  background: var(--primary);
  color: white;
}

.sidebar-item.completed .sidebar-item-number {
  background: var(--success);
  color: white;
}

/* Main Content */
.main {
  margin-left: var(--sidebar-width);
  margin-top: var(--header-height);
  min-height: calc(100vh - var(--header-height));
}

.content {
  max-width: 900px;
  margin: 0 auto;
  padding: 48px 48px 96px;
}

/* Overlay for mobile */
.overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.5);
  z-index: 40;
}

.overlay.open {
  display: block;
}