:root {
    --bg-color: #f9f9f9;
    --text-color: #333;
    --link-color: #0056b3;
    --border-color: #ddd;
    --card-bg: #fff;
    --header-bg: #fff;
    --font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen-Sans, Ubuntu, Cantarell, "Helvetica Neue", sans-serif;
}

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

body {
    font-family: var(--font-family);
    line-height: 1.6;
    color: var(--text-color);
    background-color: var(--bg-color);
}

a { color: var(--link-color); text-decoration: none; }
a:hover { text-decoration: underline; }

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

.site-header {
    background: var(--header-bg);
    border-bottom: 1px solid var(--border-color);
    padding: 15px 0;
    margin-bottom: 20px;
}
.site-header .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}
.site-header .logo {
    font-size: 1.5rem;
    font-weight: bold;
    color: var(--text-color);
    text-decoration: none;
}
.site-header nav ul { list-style: none; display: flex; gap: 15px; }

.layout-sidebar {
    display: grid;
    grid-template-columns: 3fr 1fr;
    gap: 30px;
}
@media (max-width: 768px) {
    .layout-sidebar { grid-template-columns: 1fr; }
}

.widget {
    background: var(--card-bg);
    padding: 20px;
    border: 1px solid var(--border-color);
    border-radius: 5px;
    margin-bottom: 20px;
}
.widget h3 { margin-bottom: 10px; font-size: 1.1rem; border-bottom: 1px solid var(--border-color); padding-bottom: 5px; }
.widget ul { list-style: none; }
.widget li { margin-bottom: 5px; }

.post-header { margin-bottom: 20px; }
.post-header h1 { font-size: 2.2rem; margin-bottom: 10px; }
.post-meta { font-size: 0.9rem; color: #666; display: flex; gap: 15px; }

.post-content h2 { margin: 30px 0 15px; border-bottom: 1px solid var(--border-color); padding-bottom: 5px; }
.post-content h3 { margin: 20px 0 10px; }
.post-content p, .post-content ul, .post-content ol { margin-bottom: 15px; }
.post-content ul, .post-content ol { padding-left: 20px; }
.post-content li { margin-bottom: 8px; }

.toc-container { margin: 20px 0; }
.toc-container ul { padding-left: 20px; }

.guide-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 20px;
    margin-top: 20px;
}
.guide-card {
    background: var(--card-bg);
    padding: 20px;
    border: 1px solid var(--border-color);
    border-radius: 5px;
}
.guide-card h3 { margin-bottom: 10px; font-size: 1.2rem; }
.guide-card .meta { font-size: 0.85rem; color: #666; margin-bottom: 10px; display: flex; justify-content: space-between;}

/* AdSense Placeholders */
.ad-placeholder {
    background-color: #e9ecef;
    border: 2px dashed #ced4da;
    display: flex;
    align-items: center;
    justify-content: center;
    color: #6c757d;
    font-size: 0.9rem;
    text-align: center;
    margin: 20px 0;
}
.ad-header { height: 90px; margin: 20px auto; max-width: 1200px; }
.ad-content { height: 250px; }
.ad-sidebar { height: 250px; margin-top: 20px; }

.site-footer {
    text-align: center;
    padding: 20px;
    margin-top: 40px;
    border-top: 1px solid var(--border-color);
    color: #666;
    font-size: 0.9rem;
}