/* Reset và biến */
:root {
    --primary-color: #4361ee;
    --secondary-color: #3f37c9;
    --success-color: #4cc9f0;
    --danger-color: #f72585;
    --warning-color: #f8961e;
    --info-color: #4895ef;
    --light-color: #f8f9fa;
    --dark-color: #212529;
    --gray-color: #6c757d;
    --border-radius: 12px;
    --box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    --transition: all 0.3s ease;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    color: var(--dark-color);
}

/* Layout chung */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 20px;
}

.card {
    background: white;
    border-radius: var(--border-radius);
    box-shadow: var(--box-shadow);
    padding: 24px;
    margin-bottom: 20px;
    transition: var(--transition);
}

.card:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 15px rgba(0, 0, 0, 0.15);
}

/* Header và Navigation */
.header {
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    padding: 15px 0;
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

.navbar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

.logo {
    font-size: 1.8rem;
    font-weight: bold;
    color: var(--primary-color);
    text-decoration: none;
}

.nav-links {
    display: flex;
    list-style: none;
    gap: 30px;
}

.nav-links a {
    text-decoration: none;
    color: var(--dark-color);
    font-weight: 500;
    transition: var(--transition);
    padding: 8px 16px;
    border-radius: var(--border-radius);
}

.nav-links a:hover,
.nav-links a.active {
    background: var(--primary-color);
    color: white;
}

/* User dropdown */
.user-menu {
    position: relative;
}

.user-button {
    background: transparent;
    border: 2px solid #e9ecef;
    border-radius: var(--border-radius);
    padding: 8px 12px;
    cursor: pointer;
    font-weight: 600;
    color: var(--dark-color);
}

.user-button:hover,
.user-button[aria-expanded="true"] {
    background: var(--primary-color);
    color: #fff;
    border-color: var(--primary-color);
}

.user-dropdown {
    position: absolute;
    right: 0;
    top: 100%;
    background: #fff;
    border: 1px solid #e9ecef;
    border-radius: 10px;
    box-shadow: var(--box-shadow);
    min-width: 160px;
    display: none;
    padding: 8px 0;
    z-index: 1002;
}

.user-dropdown.show {
    display: block;
}

/* Open dropdown on hover as well */
.user-menu:hover .user-dropdown {
    display: block;
}
.user-menu:hover .avatar-button {
    background: var(--primary-color);
    color: #fff;
    border-color: var(--primary-color);
}

.dropdown-item {
    display: block;
    padding: 10px 14px;
    color: var(--dark-color);
    text-decoration: none;
    font-weight: 500;
}

.dropdown-item:hover {
    background: #f6f8ff;
}

.dropdown-item.danger {
    color: var(--danger-color);
}

/* Avatar button */
.avatar-button {
    width: 36px;
    height: 36px;
    border-radius: 50%;
    border: 2px solid #e9ecef;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    background: #eef2ff;
    color: #3f37c9;
    font-weight: 700;
    cursor: pointer;
}

.avatar-button:hover,
.avatar-button[aria-expanded="true"] {
    background: var(--primary-color);
    color: #fff;
    border-color: var(--primary-color);
}

/* Form styles */
.form-container {
    max-width: 400px;
    margin: 50px auto;
    padding: 40px;
    background: white;
    border-radius: var(--border-radius);
    box-shadow: var(--box-shadow);
}

.form-group {
    margin-bottom: 20px;
}

.form-group label {
    display: block;
    margin-bottom: 8px;
    font-weight: 500;
    color: var(--dark-color);
}

.form-control {
    width: 100%;
    padding: 12px 16px;
    border: 2px solid #e9ecef;
    border-radius: var(--border-radius);
    font-size: 16px;
    transition: var(--transition);
}

.form-control:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(67, 97, 238, 0.1);
}

.btn {
    padding: 12px 24px;
    border: none;
    border-radius: var(--border-radius);
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    text-decoration: none;
    display: inline-block;
    text-align: center;
}

.btn-primary {
    background: var(--primary-color);
    color: white;
}

.btn-primary:hover {
    background: var(--secondary-color);
    transform: translateY(-1px);
}

.btn-success {
    background: var(--success-color);
    color: white;
}

.btn-danger {
    background: var(--danger-color);
    color: white;
}

/* Dashboard */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 20px;
    margin-bottom: 30px;
}

.stat-card {
    text-align: center;
    padding: 30px 20px;
}

.stat-card .number {
    font-size: 2.5rem;
    font-weight: bold;
    margin-bottom: 10px;
    color: var(--primary-color);
}

.stat-card .label {
    color: var(--gray-color);
    font-size: 0.9rem;
}

/* Charts */
.chart-container {
    height: 300px;
    margin: 20px 0;
}

/* Tables */
.table {
    width: 100%;
    border-collapse: collapse;
    margin-top: 20px;
}

.table th,
.table td {
    padding: 12px;
    text-align: left;
    border-bottom: 1px solid #e9ecef;
}

.table th {
    background: var(--light-color);
    font-weight: 600;
}

/* Mobile Navigation */
.menu-toggle {
    display: none;
    background: none;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    color: var(--dark-color);
}

/* Responsive Design */
@media (max-width: 768px) {
    .container {
        padding: 10px;
    }
    
    .navbar {
        flex-wrap: wrap;
    }
    
    .menu-toggle {
        display: block;
    }
    
    .nav-links {
        display: none;
        flex-direction: column;
        width: 100%;
        margin-top: 20px;
    }
    
    .nav-links.active {
        display: flex;
    }
    
    .stats-grid {
        grid-template-columns: 1fr;
    }
    
    .form-container {
        margin: 20px auto;
        padding: 20px;
    }
    
    .table {
        font-size: 0.9rem;
    }
    
    .table th,
    .table td {
        padding: 8px 4px;
    }
}

/* Animation */
@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.fade-in {
    animation: fadeIn 0.5s ease-out;
}

/* Loading spinner */
.loading {
    display: inline-block;
    width: 20px;
    height: 20px;
    border: 3px solid #f3f3f3;
    border-top: 3px solid var(--primary-color);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

/* Toast notifications */
.toast {
    position: fixed;
    top: 20px;
    right: 20px;
    padding: 15px 20px;
    background: white;
    border-radius: var(--border-radius);
    box-shadow: var(--box-shadow);
    transform: translateX(400px);
    transition: var(--transition);
    z-index: 1001;
}

.toast.show {
    transform: translateX(0);
}

.toast.success {
    border-left: 4px solid var(--success-color);
}

.toast.error {
    border-left: 4px solid var(--danger-color);
}

/* Footer */
.footer {
    margin-top: 30px;
    padding: 16px 0;
    background: rgba(255,255,255,0.92);
    border-top: 1px solid #e9ecef;
}
.footer .footer-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
    display: flex;
    flex-wrap: wrap;
    gap: 12px 20px;
    align-items: center;
    color: var(--gray-color);
}
.footer .footer-content a {
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 600;
}
.footer .footer-content a:hover {
    text-decoration: underline;
}

/* Auth pages */
.auth-container {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    padding: 20px;
}

.auth-card {
    background: white;
    padding: 40px;
    border-radius: 15px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.2);
    width: 100%;
    max-width: 400px;
}

.auth-header {
    text-align: center;
    margin-bottom: 30px;
}

.auth-header h2 {
    color: #4361ee;
    margin-bottom: 10px;
}

.password-input-wrapper {
    position: relative;
}

.password-toggle {
    position: absolute;
    right: 12px;
    top: 50%;
    transform: translateY(-50%);
    background: none;
    border: none;
    color: #6c757d;
    cursor: pointer;
}