/* Reset và Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --primary: #2563eb;
    --primary-dark: #1d4ed8;
    --secondary: #60a5fa;
    --success: #10b981;
    --danger: #ef4444;
    --warning: #f59e0b;
    --info: #3b82f6;
    --dark: #1f2937;
    --light: #f8fafc;
    --white: #ffffff;
    --border: #e2e8f0;
    --shadow: 0 6px 14px -8px rgba(15, 23, 42, 0.2);
    --shadow-lg: 0 16px 24px -12px rgba(15, 23, 42, 0.25);
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: #f8fafc;
    min-height: 100vh;
    color: var(--dark);
}

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

/* Header */
.main-header {
    background: var(--white);
    box-shadow: var(--shadow);
    position: sticky;
    top: 0;
    z-index: 1000;
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 0;
}

.logo a {
    font-size: 1.5rem;
    font-weight: bold;
    color: var(--primary);
    text-decoration: none;
}

.brand {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.brand-logo {
    width: 32px;
    height: 32px;
    object-fit: contain;
}

.brand-text {
    display: flex;
    flex-direction: column;
}

.brand-name {
    font-size: 0.95rem;
    font-weight: 700;
    color: var(--dark);
    line-height: 1.2;
}

.brand-sub {
    font-size: 0.8rem;
    color: #6b7280;
}

.main-nav ul {
    display: flex;
    list-style: none;
    gap: 0.5rem;
}

.main-nav a {
    padding: 0.5rem 1rem;
    text-decoration: none;
    color: var(--dark);
    border-radius: 8px;
    transition: all 0.3s;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.main-nav a:hover {
    background: #f1f5f9;
    transform: translateY(-2px);
}

.user-menu {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.dropdown {
    position: relative;
}

.dropdown-toggle {
    background: var(--light);
    border: none;
    padding: 0.5rem 1rem;
    border-radius: 8px;
    cursor: pointer;
    font-size: 1.2rem;
}

.dropdown-menu {
    display: none;
    position: absolute;
    right: 0;
    top: 100%;
    background: var(--white);
    box-shadow: var(--shadow-lg);
    border-radius: 8px;
    min-width: 150px;
    margin-top: 0.5rem;
}

.dropdown:hover .dropdown-menu {
    display: block;
}

.dropdown-menu a {
    display: block;
    padding: 0.75rem 1rem;
    color: var(--dark);
    text-decoration: none;
    transition: background 0.2s;
}

.dropdown-menu a:hover {
    background: var(--light);
}

/* Main Content */
.main-content {
    padding: 2rem 0;
    min-height: calc(100vh - 200px);
}

/* Cards */
.card {
    background: var(--white);
    border-radius: 12px;
    box-shadow: var(--shadow);
    margin-bottom: 1.5rem;
    overflow: hidden;
    transition: transform 0.3s, box-shadow 0.3s;
}

.card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

.card-header {
    padding: 1.5rem;
    border-bottom: 1px solid var(--border);
    background: var(--light);
    color: var(--dark);
}

.card-body {
    padding: 1.5rem;
}

/* Stats Cards */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1.5rem;
    margin-bottom: 2rem;
}

.stat-card {
    background: var(--white);
    padding: 1.5rem;
    border-radius: 12px;
    box-shadow: var(--shadow);
    display: flex;
    align-items: center;
    gap: 1rem;
    transition: all 0.3s;
}

.stat-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

.stat-icon {
    font-size: 3rem;
    opacity: 0.8;
}

.stat-info h3 {
    font-size: 2rem;
    margin-bottom: 0.5rem;
    color: var(--primary);
}

.stat-info p {
    color: #6b7280;
    font-size: 0.9rem;
}

/* Forms */
.form-group {
    margin-bottom: 1.5rem;
}

.form-group label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 600;
    color: var(--dark);
}

.form-group input,
.form-group select,
.form-group textarea {
    width: 100%;
    padding: 0.75rem;
    border: 2px solid var(--border);
    border-radius: 8px;
    font-size: 1rem;
    transition: all 0.3s;
}

.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
}

.form-text {
    display: block;
    margin-top: 0.25rem;
    font-size: 0.875rem;
    color: #6b7280;
}

/* Buttons */
.btn {
    padding: 0.75rem 1.5rem;
    border: none;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s;
    text-decoration: none;
    display: inline-block;
}

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

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.btn-secondary {
    background: var(--light);
    color: var(--dark);
}

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

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

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

.btn-block {
    width: 100%;
}

.btn-sm {
    padding: 0.5rem 1rem;
    font-size: 0.875rem;
}

/* Tables */
.table-responsive {
    overflow-x: auto;
}

table {
    width: 100%;
    border-collapse: collapse;
}

table th,
table td {
    padding: 1rem;
    text-align: left;
    border-bottom: 1px solid var(--border);
}

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

table tr:hover {
    background: var(--light);
}

.table-actions {
    display: flex;
    gap: 0.5rem;
}

/* Alerts */
.alert {
    padding: 1rem;
    border-radius: 8px;
    margin-bottom: 1rem;
}

.alert-success {
    background: #d1fae5;
    color: #065f46;
    border-left: 4px solid var(--success);
}

.alert-error {
    background: #fee2e2;
    color: #991b1b;
    border-left: 4px solid var(--danger);
}

.alert-warning {
    background: #fef3c7;
    color: #92400e;
    border-left: 4px solid var(--warning);
}

.alert-info {
    background: #dbeafe;
    color: #1e40af;
    border-left: 4px solid var(--info);
}

/* Login Page */
.login-page {
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 100vh;
}

.login-container {
    width: 100%;
    max-width: 400px;
    padding: 2rem;
}

.login-box {
    background: var(--white);
    padding: 2rem;
    border-radius: 16px;
    box-shadow: var(--shadow-lg);
}

.login-header {
    text-align: center;
    margin-bottom: 2rem;
}

.login-header h1 {
    color: var(--primary);
    margin-bottom: 0.5rem;
}

.login-footer {
    text-align: center;
    margin-top: 1.5rem;
}

/* Backup Codes */
.backup-codes {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 1rem;
    margin: 1rem 0;
}

.backup-code {
    background: var(--light);
    padding: 1rem;
    border-radius: 8px;
    text-align: center;
    font-family: monospace;
    font-size: 1.1rem;
    font-weight: bold;
}

/* Page Header */
.page-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 2rem;
}

.page-header h1 {
    color: var(--dark);
    font-size: 2rem;
}

/* Pagination */
.pagination {
    display: flex;
    gap: 0.5rem;
    justify-content: center;
    margin-top: 2rem;
}

.pagination a,
.pagination span {
    padding: 0.5rem 1rem;
    background: var(--white);
    border-radius: 8px;
    text-decoration: none;
    color: var(--dark);
}

.pagination a:hover {
    background: var(--primary);
    color: var(--white);
}

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

/* Footer */
.main-footer {
    background: var(--white);
    padding: 2rem 0;
    text-align: center;
    margin-top: 3rem;
    box-shadow: 0 -4px 6px -1px rgba(0, 0, 0, 0.1);
}

.footer-info {
    margin-bottom: 1rem;
    color: #374151;
    line-height: 1.6;
}

.footer-copy {
    color: #6b7280;
    font-size: 0.9rem;
}

/* Utilities */
.text-center {
    text-align: center;
}

.text-muted {
    color: #6b7280;
}

.mt-1 { margin-top: 0.5rem; }
.mt-2 { margin-top: 1rem; }
.mt-3 { margin-top: 1.5rem; }
.mb-1 { margin-bottom: 0.5rem; }
.mb-2 { margin-bottom: 1rem; }
.mb-3 { margin-bottom: 1.5rem; }

/* Print Styles */
@media print {
    .main-header,
    .main-footer,
    .btn,
    .table-actions {
        display: none !important;
    }
    
    body {
        background: white;
    }
    
    .card {
        box-shadow: none;
        border: 1px solid #000;
    }
}

/* Responsive */
@media (max-width: 768px) {
    .header-content {
        flex-direction: column;
        gap: 1rem;
    }
    
    .main-nav ul {
        flex-wrap: wrap;
        justify-content: center;
    }
    
    .stats-grid {
        grid-template-columns: 1fr;
    }
    
    .page-header {
        flex-direction: column;
        gap: 1rem;
    }
    
    .table-responsive {
        font-size: 0.875rem;
    }
}