:root {
    --primary-color: #3498db;
    --secondary-color: #2c3e50;
    --danger-color: #e74c3c;
    --success-color: #27ae60;
    --background: #f5f5f5;
    --card-background: #ffffff;
    --text-color: #333333;
    --border-color: #ddd;
    --shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

* {
    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: var(--text-color);
    line-height: 1.6;
}

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

header {
    text-align: center;
    margin-bottom: 40px;
    padding: 30px 0;
    background-color: var(--card-background);
    border-radius: 10px;
    box-shadow: var(--shadow);
}

header h1 {
    color: var(--primary-color);
    font-size: 2.5em;
    margin-bottom: 10px;
}

header p {
    color: #666;
    font-size: 1.1em;
}

.input-section {
    background-color: var(--card-background);
    padding: 30px;
    border-radius: 10px;
    box-shadow: var(--shadow);
    margin-bottom: 30px;
}

.input-section h2 {
    color: var(--secondary-color);
    margin-bottom: 20px;
}

#bookmarkForm {
    display: grid;
    gap: 15px;
}

input[type="text"],
input[type="url"],
select {
    width: 100%;
    padding: 12px;
    border: 2px solid var(--border-color);
    border-radius: 5px;
    font-size: 16px;
    transition: border-color 0.3s;
}

input[type="text"]:focus,
input[type="url"]:focus,
select:focus {
    outline: none;
    border-color: var(--primary-color);
}

button {
    padding: 12px 24px;
    background-color: var(--primary-color);
    color: white;
    border: none;
    border-radius: 5px;
    font-size: 16px;
    cursor: pointer;
    transition: background-color 0.3s;
}

button:hover {
    background-color: #2980b9;
}

.filter-section {
    background-color: var(--card-background);
    padding: 30px;
    border-radius: 10px;
    box-shadow: var(--shadow);
    margin-bottom: 30px;
}

.filter-section h2 {
    color: var(--secondary-color);
    margin-bottom: 20px;
}

.filter-controls {
    display: grid;
    grid-template-columns: 1fr 1fr 1fr;
    gap: 15px;
}

.action-buttons {
    display: flex;
    gap: 15px;
    margin-bottom: 30px;
    flex-wrap: wrap;
}

#exportBtn {
    background-color: var(--success-color);
}

#exportBtn:hover {
    background-color: #229954;
}

#importBtn {
    background-color: var(--secondary-color);
}

#importBtn:hover {
    background-color: #1a252f;
}

#clearBtn {
    background-color: var(--danger-color);
}

#clearBtn:hover {
    background-color: #c0392b;
}

.bookmarks-section {
    background-color: var(--card-background);
    padding: 30px;
    border-radius: 10px;
    box-shadow: var(--shadow);
}

.bookmarks-section h2 {
    color: var(--secondary-color);
    margin-bottom: 20px;
}

.sort-controls {
    margin-bottom: 20px;
}

.sort-controls label {
    margin-right: 10px;
    font-weight: bold;
}

.bookmarks-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 20px;
}

.bookmark-card {
    background-color: #f9f9f9;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 20px;
    transition: all 0.3s;
    position: relative;
}

.bookmark-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 5px 20px rgba(0, 0, 0, 0.15);
}

.bookmark-card h3 {
    margin-bottom: 10px;
    color: var(--secondary-color);
    font-size: 1.1em;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

.bookmark-card a {
    color: var(--primary-color);
    text-decoration: none;
    font-size: 0.9em;
    display: block;
    margin-bottom: 10px;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

.bookmark-card a:hover {
    text-decoration: underline;
}

.bookmark-meta {
    display: flex;
    flex-direction: column;
    gap: 5px;
    margin-bottom: 10px;
}

.category-badge {
    display: inline-block;
    padding: 4px 12px;
    background-color: var(--primary-color);
    color: white;
    border-radius: 20px;
    font-size: 0.8em;
    width: fit-content;
}

.tags {
    display: flex;
    flex-wrap: wrap;
    gap: 5px;
    margin-top: 10px;
}

.tag {
    display: inline-block;
    padding: 4px 10px;
    background-color: #ecf0f1;
    color: #7f8c8d;
    border-radius: 15px;
    font-size: 0.8em;
}

.bookmark-date {
    font-size: 0.8em;
    color: #999;
    margin-top: 10px;
}

.delete-btn {
    position: absolute;
    top: 10px;
    right: 10px;
    background-color: var(--danger-color);
    color: white;
    border: none;
    border-radius: 50%;
    width: 30px;
    height: 30px;
    cursor: pointer;
    font-size: 16px;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: background-color 0.3s;
}

.delete-btn:hover {
    background-color: #c0392b;
}

.empty-state {
    text-align: center;
    padding: 60px 20px;
    color: #999;
}

.empty-state h3 {
    font-size: 1.5em;
    margin-bottom: 10px;
}

@media (max-width: 768px) {
    .filter-controls {
        grid-template-columns: 1fr;
    }
    
    .bookmarks-grid {
        grid-template-columns: 1fr;
    }
    
    header h1 {
        font-size: 2em;
    }
    
    .action-buttons {
        justify-content: center;
    }
}