:root {
    --primary-color: #2196F3;
    --success-color: #4CAF50;
    --warning-color: #FFC107;
    --danger-color: #F44336;
    --purple-color: #9C27B0;
    --background-color: #f5f5f5;
    --surface-color: #ffffff;
    --text-primary: #212121;
    --text-secondary: #757575;
    --border-color: #e0e0e0;
    --shadow: 0 2px 4px rgba(0,0,0,0.1);
    --shadow-elevated: 0 4px 8px rgba(0,0,0,0.15);
    --border-radius: 8px;
    --transition: all 0.3s ease;
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    background-color: var(--background-color);
    color: var(--text-primary);
    line-height: 1.6;
    padding-bottom: 80px;
}

/* Header */
.app-header {
    background: var(--surface-color);
    padding: 1rem;
    box-shadow: var(--shadow);
    position: sticky;
    top: 0;
    z-index: 100;
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 1rem;
}

.app-header h1 {
    font-size: 1.5rem;
    color: var(--primary-color);
    font-weight: 600;
}

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

/* Buttons */
.btn {
    padding: 0.5rem 1rem;
    border: none;
    border-radius: var(--border-radius);
    font-size: 0.9rem;
    font-weight: 500;
    cursor: pointer;
    transition: var(--transition);
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    text-decoration: none;
    white-space: nowrap;
}

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

.btn-primary:hover {
    background: #1976D2;
    transform: translateY(-1px);
}

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

.btn-secondary:hover {
    background: #616161;
    transform: translateY(-1px);
}

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

.btn-success:hover {
    background: #388E3C;
}

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

.btn-warning:hover {
    background: #F57F17;
}

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

.btn-danger:hover {
    background: #D32F2F;
}

.btn:disabled {
    opacity: 0.6;
    cursor: not-allowed;
    transform: none;
}

/* Main Content */
.main-content {
    padding: 1rem;
    max-width: 1200px;
    margin: 0 auto;
}

.content-section {
    display: none;
}

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

.section-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1.5rem;
    flex-wrap: wrap;
    gap: 1rem;
}

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

/* Search Container */
.search-container {
    background: var(--surface-color);
    padding: 1.5rem;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    margin-bottom: 1.5rem;
}

.search-box {
    position: relative;
    margin-bottom: 1rem;
}

.search-box i {
    position: absolute;
    left: 1rem;
    top: 50%;
    transform: translateY(-50%);
    color: var(--text-secondary);
}

.search-box input {
    width: 100%;
    padding: 0.75rem 1rem 0.75rem 2.5rem;
    border: 2px solid var(--border-color);
    border-radius: var(--border-radius);
    font-size: 1rem;
    transition: var(--transition);
}

.search-box input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(33, 150, 243, 0.1);
}

.clear-btn {
    position: absolute;
    right: 0.5rem;
    top: 50%;
    transform: translateY(-50%);
    background: none;
    border: none;
    color: var(--text-secondary);
    cursor: pointer;
    padding: 0.25rem;
    border-radius: 50%;
    display: none;
}

.clear-btn:hover {
    background: var(--border-color);
}

.clear-btn.visible {
    display: block;
}

.search-filters {
    display: flex;
    gap: 1rem;
    flex-wrap: wrap;
}

.search-filters select {
    flex: 1;
    min-width: 150px;
    padding: 0.5rem;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    background: white;
    font-size: 0.9rem;
}

/* Stats Container */
.stats-container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(120px, 1fr));
    gap: 1rem;
    margin-bottom: 1.5rem;
}

.stat-card {
    background: var(--surface-color);
    padding: 1rem;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    display: flex;
    align-items: center;
    gap: 0.75rem;
    transition: var(--transition);
}

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

.stat-card i {
    font-size: 1.5rem;
    color: var(--primary-color);
}

.stat-number {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--text-primary);
    display: block;
}

.stat-label {
    font-size: 0.8rem;
    color: var(--text-secondary);
    display: block;
}

/* Bookmarks Container */
.bookmarks-container {
    background: var(--surface-color);
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    overflow: hidden;
}

.bookmarks-list {
    display: flex;
    flex-direction: column;
}

.bookmark-item {
    padding: 1rem;
    border-bottom: 1px solid var(--border-color);
    transition: var(--transition);
    position: relative;
}

.bookmark-item:last-child {
    border-bottom: none;
}

.bookmark-item:hover {
    background: #f8f9fa;
}

.bookmark-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 0.5rem;
    gap: 1rem;
}

.bookmark-info {
    flex: 1;
    min-width: 0;
}

.bookmark-title {
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 0.25rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.bookmark-title a {
    color: inherit;
    text-decoration: none;
    word-break: break-word;
}

.bookmark-title a:hover {
    color: var(--primary-color);
}

.bookmark-url {
    font-size: 0.85rem;
    color: var(--text-secondary);
    word-break: break-all;
    margin-bottom: 0.5rem;
}

.bookmark-description {
    font-size: 0.9rem;
    color: var(--text-primary);
    margin-bottom: 0.5rem;
}

.bookmark-meta {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    align-items: center;
    margin-bottom: 0.5rem;
}

.bookmark-category {
    display: inline-flex;
    align-items: center;
    gap: 0.25rem;
    padding: 0.25rem 0.5rem;
    background: var(--primary-color);
    color: white;
    border-radius: 12px;
    font-size: 0.75rem;
    font-weight: 500;
}

.bookmark-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 0.25rem;
}

.bookmark-tag {
    padding: 0.125rem 0.375rem;
    background: var(--border-color);
    color: var(--text-secondary);
    border-radius: 8px;
    font-size: 0.7rem;
}

.bookmark-status {
    display: flex;
    align-items: center;
    gap: 0.25rem;
    font-size: 0.75rem;
    font-weight: 500;
}

.bookmark-status.active {
    color: var(--success-color);
}

.bookmark-status.dead {
    color: var(--danger-color);
}

.bookmark-status.duplicate {
    color: var(--warning-color);
}

.bookmark-status.checking {
    color: var(--text-secondary);
}

.bookmark-actions {
    display: flex;
    gap: 0.5rem;
    flex-shrink: 0;
}

.bookmark-actions .btn {
    padding: 0.25rem 0.5rem;
    font-size: 0.8rem;
}

.empty-state {
    text-align: center;
    padding: 3rem 1rem;
    color: var(--text-secondary);
}

.empty-state i {
    font-size: 3rem;
    margin-bottom: 1rem;
    color: var(--border-color);
}

.empty-state h3 {
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

/* Categories */
.categories-list {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
    gap: 1rem;
}

.category-card {
    background: var(--surface-color);
    padding: 1.5rem;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    transition: var(--transition);
    position: relative;
}

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

.category-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 1rem;
}

.category-info {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.category-icon {
    font-size: 1.5rem;
}

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

.category-actions {
    display: flex;
    gap: 0.25rem;
}

.category-actions .btn {
    padding: 0.25rem;
    font-size: 0.8rem;
}

.category-stats {
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-bottom: 0.5rem;
}

.category-keywords {
    font-size: 0.8rem;
    color: var(--text-secondary);
}

/* Settings */
.settings-container {
    display: flex;
    flex-direction: column;
    gap: 2rem;
}

.setting-group {
    background: var(--surface-color);
    padding: 1.5rem;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
}

.setting-group h3 {
    margin-bottom: 1rem;
    color: var(--text-primary);
    border-bottom: 2px solid var(--border-color);
    padding-bottom: 0.5rem;
}

.setting-item {
    margin-bottom: 1rem;
}

.setting-item:last-child {
    margin-bottom: 0;
}

.setting-item label {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-weight: 500;
    margin-bottom: 0.25rem;
    cursor: pointer;
}

.setting-item input[type="checkbox"] {
    width: 1.2rem;
    height: 1.2rem;
    accent-color: var(--primary-color);
}

.setting-item select {
    width: 100%;
    padding: 0.5rem;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    background: white;
    font-size: 0.9rem;
}

.setting-description {
    font-size: 0.85rem;
    color: var(--text-secondary);
    margin-top: 0.25rem;
}

.setting-actions {
    display: flex;
    gap: 1rem;
    flex-wrap: wrap;
}

/* FAQ */
.faq-container {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.faq-item {
    background: var(--surface-color);
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    overflow: hidden;
}

.faq-question {
    width: 100%;
    padding: 1rem;
    background: none;
    border: none;
    text-align: left;
    font-size: 1rem;
    font-weight: 500;
    color: var(--text-primary);
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
    transition: var(--transition);
}

.faq-question:hover {
    background: #f8f9fa;
}

.faq-icon {
    font-size: 1.2rem;
    color: var(--primary-color);
    transition: var(--transition);
}

.faq-question[aria-expanded="true"] .faq-icon {
    transform: rotate(45deg);
}

.faq-answer {
    padding: 0 1rem 1rem;
    color: var(--text-secondary);
    line-height: 1.6;
    animation: fadeIn 0.3s ease;
}

.faq-answer[hidden] {
    display: none;
}

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

/* Modals */
.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.5);
    z-index: 1000;
    padding: 1rem;
    overflow-y: auto;
}

.modal.active {
    display: flex;
    align-items: center;
    justify-content: center;
}

.modal-content {
    background: var(--surface-color);
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-elevated);
    width: 100%;
    max-width: 500px;
    max-height: 90vh;
    overflow-y: auto;
    animation: modalSlideIn 0.3s ease;
}

@keyframes modalSlideIn {
    from {
        opacity: 0;
        transform: translateY(-50px) scale(0.95);
    }
    to {
        opacity: 1;
        transform: translateY(0) scale(1);
    }
}

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

.modal-header h3 {
    margin: 0;
    color: var(--text-primary);
}

.modal-close {
    background: none;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    color: var(--text-secondary);
    padding: 0;
    width: 2rem;
    height: 2rem;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 50%;
    transition: var(--transition);
}

.modal-close:hover {
    background: var(--border-color);
}

/* Forms */
form {
    padding: 1rem;
}

.form-group {
    margin-bottom: 1rem;
}

.form-group label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 500;
    color: var(--text-primary);
}

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

.form-group input:focus,
.form-group textarea:focus,
.form-group select:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(33, 150, 243, 0.1);
}

.form-group textarea {
    resize: vertical;
    min-height: 80px;
}

.form-group small {
    display: block;
    margin-top: 0.25rem;
    font-size: 0.8rem;
    color: var(--text-secondary);
}

.form-actions {
    display: flex;
    gap: 1rem;
    justify-content: flex-end;
    margin-top: 1.5rem;
    padding-top: 1rem;
    border-top: 1px solid var(--border-color);
}

/* Bottom Navigation */
.bottom-nav {
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    background: var(--surface-color);
    border-top: 1px solid var(--border-color);
    display: flex;
    justify-content: space-around;
    padding: 0.5rem 0;
    z-index: 100;
}

.nav-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.25rem;
    padding: 0.5rem;
    text-decoration: none;
    color: var(--text-secondary);
    transition: var(--transition);
    border-radius: var(--border-radius);
    min-width: 60px;
}

.nav-item:hover {
    background: #f8f9fa;
}

.nav-item.active {
    color: var(--primary-color);
}

.nav-item i {
    font-size: 1.2rem;
}

.nav-item span {
    font-size: 0.7rem;
    font-weight: 500;
}

/* Footer */
footer {
    text-align: center;
    padding: 2rem 1rem 1rem;
    color: var(--text-secondary);
    font-size: 0.85rem;
    margin-top: 2rem;
}

/* Loading States */
.loading {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
}

.loading::after {
    content: '';
    width: 1rem;
    height: 1rem;
    border: 2px solid var(--border-color);
    border-top: 2px solid var(--primary-color);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

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

/* Notifications */
.notification {
    position: fixed;
    top: 1rem;
    right: 1rem;
    background: var(--surface-color);
    padding: 1rem;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-elevated);
    border-left: 4px solid var(--primary-color);
    z-index: 1001;
    max-width: 300px;
    animation: slideInRight 0.3s ease;
}

.notification.success {
    border-left-color: var(--success-color);
}

.notification.error {
    border-left-color: var(--danger-color);
}

.notification.warning {
    border-left-color: var(--warning-color);
}

@keyframes slideInRight {
    from {
        opacity: 0;
        transform: translateX(100%);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

/* Responsive Design */
@media (max-width: 768px) {
    .app-header {
        padding: 0.75rem;
    }
    
    .app-header h1 {
        font-size: 1.25rem;
    }
    
    .main-content {
        padding: 0.75rem;
    }
    
    .search-filters {
        flex-direction: column;
    }
    
    .search-filters select {
        min-width: auto;
    }
    
    .stats-container {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .bookmark-header {
        flex-direction: column;
        align-items: stretch;
        gap: 0.5rem;
    }
    
    .bookmark-actions {
        justify-content: flex-start;
    }
    
    .categories-list {
        grid-template-columns: 1fr;
    }
    
    .setting-actions {
        flex-direction: column;
    }
    
    .form-actions {
        flex-direction: column-reverse;
    }
    
    .modal-content {
        margin: 0.5rem;
        max-height: calc(100vh - 1rem);
    }
}

@media (max-width: 480px) {
    .stats-container {
        grid-template-columns: 1fr;
    }
    
    .header-actions {
        width: 100%;
        justify-content: center;
    }
    
    .section-header {
        flex-direction: column;
        align-items: stretch;
    }
    
    .nav-item span {
        font-size: 0.6rem;
    }
}

/* Dark mode support */
@media (prefers-color-scheme: dark) {
    :root {
        --background-color: #121212;
        --surface-color: #1e1e1e;
        --text-primary: #ffffff;
        --text-secondary: #b0b0b0;
        --border-color: #333333;
    }
    
    .bookmark-item:hover {
        background: #2a2a2a;
    }
    
    .faq-question:hover {
        background: #2a2a2a;
    }
    
    .nav-item:hover {
        background: #2a2a2a;
    }
    
    .form-group input,
    .form-group textarea,
    .form-group select {
        background: var(--surface-color);
        color: var(--text-primary);
    }
}

/* Print styles */
@media print {
    .app-header,
    .bottom-nav,
    .bookmark-actions,
    .category-actions,
    .setting-actions,
    .modal {
        display: none !important;
    }
    
    .main-content {
        padding: 0;
    }
    
    .content-section {
        display: block !important;
    }
    
    .bookmark-item {
        break-inside: avoid;
        margin-bottom: 1rem;
    }
}