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

:root {
    --bg-primary: #0f0f0f;
    --bg-secondary: #1a1a1a;
    --bg-card: #252525;
    --text-primary: #e0e0e0;
    --text-secondary: #a0a0a0;
    --accent: #3b82f6;
    --accent-hover: #2563eb;
    --border: #333;
}

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

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

header {
    background-color: var(--bg-secondary);
    padding: 30px 0;
    border-bottom: 1px solid var(--border);
}

header h1 {
    font-size: 2.5rem;
    margin-bottom: 10px;
}

.subtitle {
    color: var(--text-secondary);
    font-size: 1.1rem;
}

.main-nav {
    background-color: var(--bg-card);
    padding: 15px 0;
    position: sticky;
    top: 0;
    z-index: 100;
    border-bottom: 1px solid var(--border);
}

.main-nav a {
    color: var(--text-primary);
    text-decoration: none;
    padding: 10px 20px;
    margin-right: 10px;
    border-radius: 5px;
    transition: all 0.3s;
}

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

.hero {
    text-align: center;
    padding: 60px 0;
}

.hero h2 {
    font-size: 2.2rem;
    margin-bottom: 15px;
}

.hero p {
    font-size: 1.2rem;
    color: var(--text-secondary);
}

.ad-slot {
    background-color: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 20px;
    margin: 30px 0;
    text-align: center;
}

.ad-placeholder {
    color: var(--text-secondary);
    padding: 35px;
    border: 2px dashed var(--border);
    border-radius: 5px;
}

.categories {
    margin: 50px 0;
}

.categories h3 {
    font-size: 1.8rem;
    margin-bottom: 30px;
}

.category-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 20px;
}

.category-card {
    background-color: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 10px;
    padding: 30px;
    text-align: center;
    text-decoration: none;
    color: var(--text-primary);
    transition: all 0.3s;
}

.category-card:hover {
    transform: translateY(-5px);
    border-color: var(--accent);
    box-shadow: 0 5px 20px rgba(59, 130, 246, 0.3);
}

.category-card .icon {
    font-size: 3rem;
    display: block;
    margin-bottom: 15px;
}

.category-card h4 {
    font-size: 1.3rem;
    margin-bottom: 10px;
}

.category-card p {
    color: var(--text-secondary);
}

.articles-section {
    margin: 50px 0;
}

.articles-section h3 {
    font-size: 1.8rem;
    margin-bottom: 30px;
}

.articles-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 25px;
}

.article-card {
    background-color: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 10px;
    padding: 25px;
    text-decoration: none;
    color: var(--text-primary);
    transition: all 0.3s;
    display: block;
}

.article-card:hover {
    transform: translateY(-3px);
    border-color: var(--accent);
}

.article-card .category-tag {
    display: inline-block;
    background-color: var(--accent);
    color: white;
    padding: 5px 12px;
    border-radius: 15px;
    font-size: 0.85rem;
    margin-bottom: 15px;
}

.article-card h4 {
    font-size: 1.2rem;
    margin-bottom: 10px;
    line-height: 1.4;
}

.article-card .excerpt {
    color: var(--text-secondary);
    font-size: 0.95rem;
    margin-bottom: 15px;
}

.article-card .meta {
    color: var(--text-secondary);
    font-size: 0.85rem;
}

.tool-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 20px;
    margin-top: 30px;
}

.tool-card {
    background-color: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 10px;
    padding: 20px;
    transition: all 0.3s;
}

.tool-card:hover {
    border-color: var(--accent);
    transform: translateY(-3px);
}

.tool-card h4 {
    font-size: 1.2rem;
    margin-bottom: 10px;
}

.tool-card .description {
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-bottom: 15px;
}

.tool-card .tags {
    margin-bottom: 15px;
}

.tool-card .tag {
    display: inline-block;
    background-color: var(--bg-secondary);
    padding: 4px 10px;
    border-radius: 12px;
    font-size: 0.8rem;
    margin-right: 8px;
    margin-bottom: 5px;
}

.tool-card .link {
    display: inline-block;
    color: var(--accent);
    text-decoration: none;
    font-size: 0.9rem;
}

.tool-card .link:hover {
    color: var(--accent-hover);
    text-decoration: underline;
}

.article-content {
    max-width: 800px;
    margin: 0 auto;
    padding: 40px 20px;
}

.article-header {
    margin-bottom: 40px;
}

.article-header h1 {
    font-size: 2.5rem;
    line-height: 1.3;
    margin-bottom: 20px;
}

.article-meta {
    color: var(--text-secondary);
    font-size: 0.95rem;
}

.article-body {
    font-size: 1.1rem;
    line-height: 1.8;
}

.article-body h2 {
    font-size: 1.8rem;
    margin: 40px 0 20px;
}

.article-body h3 {
    font-size: 1.4rem;
    margin: 30px 0 15px;
}

.article-body p {
    margin-bottom: 20px;
}

.article-body ul,
.article-body ol {
    margin: 20px 0;
    padding-left: 30px;
}

.article-body li {
    margin-bottom: 10px;
}

.article-body strong {
    color: var(--accent);
}

.article-body code {
    background-color: var(--bg-card);
    padding: 2px 6px;
    border-radius: 3px;
    font-family: 'Courier New', monospace;
}

.article-body blockquote {
    border-left: 4px solid var(--accent);
    padding-left: 20px;
    margin: 20px 0;
    color: var(--text-secondary);
    font-style: italic;
}

.filter-section {
    margin: 30px 0;
    padding: 20px;
    background-color: var(--bg-card);
    border-radius: 10px;
}

.filter-buttons {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
}

.filter-btn {
    background-color: var(--bg-secondary);
    color: var(--text-primary);
    border: 1px solid var(--border);
    padding: 8px 16px;
    border-radius: 20px;
    cursor: pointer;
    transition: all 0.3s;
}

.filter-btn:hover,
.filter-btn.active {
    background-color: var(--accent);
    border-color: var(--accent);
    color: white;
}

footer {
    background-color: var(--bg-secondary);
    border-top: 1px solid var(--border);
    padding: 30px 0;
    margin-top: 80px;
    text-align: center;
    color: var(--text-secondary);
}

@media (max-width: 768px) {
    header h1 {
        font-size: 2rem;
    }

    .hero h2 {
        font-size: 1.6rem;
    }

    .category-grid {
        grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    }

    .articles-grid {
        grid-template-columns: 1fr;
    }

    .article-header h1 {
        font-size: 1.8rem;
    }
}