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

:root {
    --primary-color: #2563eb;
    --secondary-color: #64748b;
    --success-color: #10b981;
    --warning-color: #f59e0b;
    --danger-color: #ef4444;
    --background-color: #f8fafc;
    --card-background: #ffffff;
    --border-color: #e2e8f0;
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --shadow: 0 1px 3px 0 rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background-color: var(--background-color);
    color: var(--text-primary);
    line-height: 1.6;
}

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

/* Header */
.header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    background: var(--card-background);
    padding: 20px;
    border-radius: 12px;
    box-shadow: var(--shadow);
    margin-bottom: 20px;
}

.header h1 {
    color: var(--primary-color);
    font-size: 1.8rem;
}

.user-info {
    display: flex;
    align-items: center;
    gap: 15px;
}

/* Navigation */
.nav-tabs {
    display: flex;
    background: var(--card-background);
    border-radius: 12px;
    padding: 5px;
    margin-bottom: 20px;
    box-shadow: var(--shadow);
    overflow-x: auto;
}

.tab-btn {
    flex: 1;
    padding: 12px 20px;
    border: none;
    background: transparent;
    color: var(--text-secondary);
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.3s ease;
    white-space: nowrap;
    font-weight: 500;
}

.tab-btn:hover {
    background: var(--background-color);
    color: var(--text-primary);
}

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

/* Tab Content */
.tab-content {
    display: none;
    animation: fadeIn 0.3s ease;
}

.tab-content.active {
    display: block;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

/* Stats Grid */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 15px;
    margin-bottom: 30px;
}

.stat-card {
    background: var(--card-background);
    padding: 20px;
    border-radius: 12px;
    box-shadow: var(--shadow);
    display: flex;
    align-items: center;
    gap: 15px;
    transition: transform 0.2s ease;
}

.stat-card:hover {
    transform: translateY(-2px);
}

.stat-card i {
    font-size: 2rem;
    color: var(--primary-color);
}

.stat-info h3 {
    font-size: 1.8rem;
    font-weight: 700;
    color: var(--text-primary);
}

.stat-info p {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

/* Section Header */
.section-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
    flex-wrap: wrap;
    gap: 15px;
}

.section-header h2 {
    color: var(--text-primary);
    font-size: 1.5rem;
}

/* Controls */
.controls {
    display: flex;
    gap: 10px;
    align-items: center;
    flex-wrap: wrap;
}

/* Buttons */
.btn {
    padding: 10px 20px;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    font-weight: 500;
    transition: all 0.2s ease;
    display: inline-flex;
    align-items: center;
    gap: 8px;
    text-decoration: none;
    font-size: 0.9rem;
}

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

.btn-primary:hover {
    background: #1d4ed8;
    transform: translateY(-1px);
}

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

.btn-success:hover {
    background: #059669;
}

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

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

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

.btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

/* Form Elements */
.form-input, .form-select {
    padding: 10px 15px;
    border: 2px solid var(--border-color);
    border-radius: 8px;
    font-size: 0.9rem;
    transition: border-color 0.2s ease;
    background: var(--card-background);
}

.form-input:focus, .form-select:focus {
    outline: none;
    border-color: var(--primary-color);
}

/* Groups Grid */
.groups-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 20px;
}

.group-card {
    background: var(--card-background);
    border-radius: 12px;
    padding: 20px;
    box-shadow: var(--shadow);
    transition: transform 0.2s ease;
}

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

.group-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 15px;
}

.group-title {
    font-size: 1.2rem;
    font-weight: 600;
    color: var(--text-primary);
}

.group-actions {
    display: flex;
    gap: 5px;
}

.group-stats {
    display: flex;
    justify-content: space-between;
    margin-bottom: 15px;
    font-size: 0.9rem;
    color: var(--text-secondary);
}

.group-subscription {
    background: var(--background-color);
    padding: 10px;
    border-radius: 6px;
    font-family: monospace;
    font-size: 0.8rem;
    word-break: break-all;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

/* Nodes Table */
.nodes-table-container {
    background: var(--card-background);
    border-radius: 12px;
    overflow: hidden;
    box-shadow: var(--shadow);
}

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

.nodes-table th {
    background: var(--background-color);
    padding: 15px;
    text-align: left;
    font-weight: 600;
    color: var(--text-primary);
    border-bottom: 2px solid var(--border-color);
}

.nodes-table td {
    padding: 15px;
    border-bottom: 1px solid var(--border-color);
}

.nodes-table tr:hover {
    background: var(--background-color);
}

.status-badge {
    padding: 4px 8px;
    border-radius: 12px;
    font-size: 0.8rem;
    font-weight: 500;
}

.status-online {
    background: #dcfce7;
    color: #166534;
}

.status-offline {
    background: #fee2e2;
    color: #991b1b;
}

/* Import Section */
.import-methods {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(400px, 1fr));
    gap: 20px;
    margin-bottom: 30px;
}

.import-method {
    background: var(--card-background);
    padding: 20px;
    border-radius: 12px;
    box-shadow: var(--shadow);
}

.import-method h3 {
    color: var(--primary-color);
    margin-bottom: 10px;
}

.import-method p {
    color: var(--text-secondary);
    margin-bottom: 15px;
    font-size: 0.9rem;
}

#importText {
    width: 100%;
    min-height: 120px;
    padding: 15px;
    border: 2px solid var(--border-color);
    border-radius: 8px;
    resize: vertical;
    font-family: monospace;
    font-size: 0.9rem;
}

.import-options {
    display: flex;
    gap: 10px;
    margin-top: 15px;
    flex-wrap: wrap;
}

.file-upload-area {
    border: 2px dashed var(--border-color);
    border-radius: 8px;
    padding: 30px;
    text-align: center;
    cursor: pointer;
    transition: all 0.2s ease;
}

.file-upload-area:hover {
    border-color: var(--primary-color);
    background: var(--background-color);
}

.file-upload-area i {
    font-size: 2rem;
    color: var(--text-secondary);
    margin-bottom: 10px;
}

/* Import Preview */
.import-preview {
    background: var(--card-background);
    border-radius: 12px;
    padding: 20px;
    box-shadow: var(--shadow);
}

.import-preview h3 {
    margin-bottom: 15px;
    color: var(--text-primary);
}

.preview-content {
    max-height: 300px;
    overflow-y: auto;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    padding: 15px;
    margin-bottom: 15px;
    font-family: monospace;
    font-size: 0.9rem;
}

.preview-actions {
    display: flex;
    gap: 10px;
    justify-content: flex-end;
}

/* Settings Form */
.settings-form {
    background: var(--card-background);
    padding: 30px;
    border-radius: 12px;
    box-shadow: var(--shadow);
    margin-bottom: 30px;
}

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

.form-group label {
    display: block;
    margin-bottom: 5px;
    font-weight: 500;
    color: var(--text-primary);
}

.form-group input {
    width: 100%;
}

/* Subscription Links */
.subscription-links {
    background: var(--card-background);
    padding: 30px;
    border-radius: 12px;
    box-shadow: var(--shadow);
}

.subscriptions-list {
    display: flex;
    flex-direction: column;
    gap: 15px;
}

.subscription-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 15px;
    background: var(--background-color);
    border-radius: 8px;
    flex-wrap: wrap;
    gap: 10px;
}

.subscription-info {
    flex: 1;
}

.subscription-name {
    font-weight: 600;
    color: var(--text-primary);
}

.subscription-url {
    font-family: monospace;
    font-size: 0.8rem;
    color: var(--text-secondary);
    word-break: break-all;
}

/* Modal */
.modal {
    display: none;
    position: fixed;
    z-index: 1000;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.5);
    animation: fadeIn 0.3s ease;
}

.modal-content {
    background-color: var(--card-background);
    margin: 5% auto;
    padding: 30px;
    border-radius: 12px;
    width: 90%;
    max-width: 600px;
    max-height: 80vh;
    overflow-y: auto;
    position: relative;
    animation: slideIn 0.3s ease;
}

@keyframes slideIn {
    from { transform: translateY(-50px); opacity: 0; }
    to { transform: translateY(0); opacity: 1; }
}

.close {
    position: absolute;
    right: 20px;
    top: 20px;
    font-size: 1.5rem;
    font-weight: bold;
    cursor: pointer;
    color: var(--text-secondary);
}

.close:hover {
    color: var(--text-primary);
}

/* Notifications */
.notifications {
    position: fixed;
    top: 20px;
    right: 20px;
    z-index: 1001;
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.notification {
    padding: 15px 20px;
    border-radius: 8px;
    color: white;
    font-weight: 500;
    box-shadow: var(--shadow-lg);
    animation: slideInRight 0.3s ease;
    cursor: pointer;
}

@keyframes slideInRight {
    from { transform: translateX(100%); }
    to { transform: translateX(0); }
}

.notification.success { background: var(--success-color); }
.notification.error { background: var(--danger-color); }
.notification.warning { background: var(--warning-color); }
.notification.info { background: var(--primary-color); }

/* Responsive Design */
@media (max-width: 768px) {
    .container {
        padding: 10px;
    }
    
    .header {
        flex-direction: column;
        gap: 15px;
        text-align: center;
    }
    
    .nav-tabs {
        flex-direction: column;
    }
    
    .stats-grid {
        grid-template-columns: 1fr;
    }
    
    .section-header {
        flex-direction: column;
        align-items: flex-start;
    }
    
    .import-methods {
        grid-template-columns: 1fr;
    }
    
    .nodes-table-container {
        overflow-x: auto;
    }
    
    .subscription-item {
        flex-direction: column;
        align-items: flex-start;
    }
}

/* Loading States */
.loading {
    opacity: 0.6;
    pointer-events: none;
}

.spinner {
    display: inline-block;
    width: 20px;
    height: 20px;
    border: 2px solid rgba(255, 255, 255, 0.3);
    border-radius: 50%;
    border-top-color: white;
    animation: spin 1s ease-in-out infinite;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

/* Utility Classes */
.text-center { text-align: center; }
.text-right { text-align: right; }
.mb-0 { margin-bottom: 0; }
.mb-1 { margin-bottom: 10px; }
.mb-2 { margin-bottom: 20px; }
.hidden { display: none; }
.visible { display: block; }