:root {
    --primary: #3b82f6;
    --primary-dark: #2563eb;
    --text-main: #111827;
    --text-muted: #6b7280;
    --bg-soft: #f9fafb;
    --white: #ffffff;
    --border: #e5e7eb;
    --danger: #ef4444;
    --warning: #f59e0b;
    --success: #10b981;
}

/* Reset & Base */
* { box-sizing: border-box; }
body { margin: 0; font-family: 'Inter', sans-serif; background: var(--bg-soft); }

/* Header */
.header {
    background: var(--white);
    height: 72px;
    position: sticky;
    top: 0;
    z-index: 100;
    border-bottom: 1px solid var(--border);
    box-shadow: 0 1px 3px rgba(0,0,0,0.05);
}

.header-content {
    max-width: 1280px;
    margin: 0 auto;
    padding: 0 24px;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.header-left {
    display: flex;
    align-items: center;
    gap: 16px;
}

.brand-logo img {
    height: 32px;
    width: auto;
}

/* Navigation */
.header-nav {
    display: flex;
    gap: 32px;
    margin: 0 40px;
}

.header-link {
    color: var(--text-muted);
    text-decoration: none;
    font-weight: 500;
    font-size: 0.95rem;
    transition: color 0.2s;
    padding: 8px 0;
    position: relative;
}

.header-link:hover, .header-link.active {
    color: var(--primary);
}

.header-link.active::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 100%;
    height: 2px;
    background: var(--primary);
    border-radius: 2px;
}

/* Actions */
.header-actions {
    display: flex;
    align-items: center;
    gap: 12px;
}

.icon-btn {
    background: transparent;
    border: none;
    padding: 8px;
    border-radius: 50%;
    color: var(--text-muted);
    cursor: pointer;
    position: relative;
    transition: all 0.2s;
    display: flex;
    align-items: center;
    justify-content: center;
}

.icon-btn:hover {
    background: var(--bg-soft);
    color: var(--text-main);
}

.badge {
    position: absolute;
    top: 0;
    right: 0;
    background: var(--danger);
    color: white;
    font-size: 10px;
    font-weight: 700;
    min-width: 16px;
    height: 16px;
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    border: 2px solid var(--white);
}

.profile-btn {
    display: flex;
    align-items: center;
    gap: 8px;
    text-decoration: none;
    color: var(--text-main);
    font-weight: 500;
    padding: 6px 12px;
    border-radius: 20px;
    background: var(--bg-soft);
    transition: all 0.2s;
}

.profile-btn:hover {
    background: #e5e7eb;
}

.header-nav-icon {
    display: none;
    align-items: center;
    justify-content: center;
    padding: 8px;
    color: var(--text-muted);
    border-radius: 8px;
    transition: all 0.2s;
}

.header-nav-icon:hover {
    background: var(--bg-soft);
    color: var(--text-main);
}

.header-nav-icon.active {
    color: var(--primary);
    background: #eff6ff;
}

/* Sidebar */
.sidebar {
    position: fixed;
    top: 0;
    left: 0;
    height: 100%;
    width: 280px;
    background: var(--white);
    z-index: 200;
    transform: translateX(-100%);
    transition: transform 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    border-right: 1px solid var(--border);
    display: flex;
    flex-direction: column;
}

.sidebar.active {
    transform: translateX(0);
}

.sidebar-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0,0,0,0.5);
    z-index: 150;
    opacity: 0;
    visibility: hidden;
    transition: all 0.3s;
    -webkit-backdrop-filter: blur(2px);
    backdrop-filter: blur(2px);
}

.sidebar-overlay.active {
    opacity: 1;
    visibility: visible;
}

.sidebar-content {
    height: 100%;
    display: flex;
    flex-direction: column;
}

.sidebar-header {
    padding: 20px;
    border-bottom: 1px solid var(--border);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.sidebar-nav {
    padding: 20px 12px;
    flex: 1;
    overflow-y: auto;
}

.nav-item {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 12px 16px;
    color: var(--text-muted);
    text-decoration: none;
    border-radius: 8px;
    margin-bottom: 4px;
    transition: all 0.2s;
    font-weight: 500;
}

.nav-item:hover, .nav-item.active {
    background: #eff6ff;
    color: var(--primary);
}

.menu-toggle {
    display: none;
    background: none;
    border: none;
    color: var(--text-main);
    cursor: pointer;
    padding: 4px;
}

/* Notifications */
.notification-dropdown {
    position: absolute;
    top: calc(100% + 10px);
    right: 0;
    width: 360px;
    background: var(--white);
    border-radius: 12px;
    box-shadow: 0 10px 40px rgba(0,0,0,0.15);
    border: 1px solid var(--border);
    opacity: 0;
    visibility: hidden;
    transform: translateY(-10px);
    transition: all 0.2s;
    z-index: 1000;
}

.notification-dropdown.active {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.notification-header {
    padding: 16px;
    border-bottom: 1px solid var(--border);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.notification-header h3 {
    margin: 0;
    font-size: 1rem;
    font-weight: 600;
}

.mark-all-read {
    background: none;
    border: none;
    color: var(--primary);
    font-size: 0.85rem;
    cursor: pointer;
    font-weight: 500;
}

.notification-list {
    max-height: 400px;
    overflow-y: auto;
}

.notification-item {
    padding: 16px;
    border-bottom: 1px solid var(--bg-soft);
    display: flex;
    gap: 12px;
    cursor: pointer;
    transition: background 0.2s;
}

.notification-item:hover {
    background: var(--bg-soft);
}

.notification-item.unread {
    background: #eff6ff;
}

.notification-icon {
    width: 36px;
    height: 36px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
}

.notification-content p {
    margin: 0;
}

.notification-title {
    font-weight: 600;
    font-size: 0.9rem;
    color: var(--text-main);
    margin-bottom: 2px !important;
}

.notification-text {
    font-size: 0.85rem;
    color: var(--text-muted);
    margin-bottom: 4px !important;
}

.notification-time {
    font-size: 0.75rem;
    color: #9ca3af;
}

.notification-footer {
    padding: 12px;
    text-align: center;
    border-top: 1px solid var(--border);
}

.notification-footer a {
    color: var(--primary);
    text-decoration: none;
    font-size: 0.9rem;
    font-weight: 500;
}

/* Mobile Responsive */
@media (max-width: 1024px) {
    .header-nav { display: none; }
    .menu-toggle { display: block; }
    .header-nav-icon { display: flex; }
}

@media (max-width: 640px) {
    .notification-dropdown {
        position: fixed;
        top: 72px;
        left: 0;
        right: 0;
        width: 100%;
        border-radius: 0;
        border-left: none;
        border-right: none;
    }
    .profile-btn span { display: none; }
}