:root {
    --bg: #fff;
    --text: #1a1a1a;
    --muted: #666;
    --link: #3451b2;
    --border: #e2e2e3;
    --code-bg: #f6f6f7;
    --tag-bg: #eef1f9;
    --sidebar-w: 260px;
}

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

body {
    font-family:
        system-ui,
        -apple-system,
        sans-serif;
    color: var(--text);
    background: var(--bg);
    line-height: 1.7;
}

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

.layout {
    display: flex;
    min-height: 100vh;
}

.sidebar {
    width: var(--sidebar-w);
    border-right: 1px solid var(--border);
    padding: 24px;
    position: sticky;
    top: 0;
    height: 100vh;
    overflow-y: auto;
    background: #fafafa;
    flex-shrink: 0;
}

.sidebar h2 {
    font-size: 14px;
    text-transform: uppercase;
    color: var(--muted);
    margin-bottom: 12px;
}

.sidebar ul {
    list-style: none;
}
.sidebar li {
    margin-bottom: 4px;
}

.sidebar a {
    font-size: 14px;
    display: block;
    padding: 4px 8px;
    border-radius: 4px;
    color: var(--text);
}

.sidebar a:hover {
    background: #e8e8ec;
    text-decoration: none;
}

/* ── Collapsible categories ── */

.cat-toggle {
    display: inline-block;
    width: 18px;
    cursor: pointer;
    color: var(--muted);
    font-size: 12px;
    user-select: none;
    vertical-align: middle;
}

.cat-toggle:hover {
    color: var(--text);
}

.cat-group > a {
    display: inline;
    vertical-align: middle;
}

.cat-pages {
    margin: 0;
}

/* ── Main content ── */

.main {
    flex: 1;
    padding: 40px 48px;
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

.main h1 {
    font-size: 28px;
    margin-bottom: 8px;
}

.main h2 {
    font-size: 22px;
    margin: 32px 0 12px;
    border-bottom: 1px solid var(--border);
    padding-bottom: 6px;
}

.main h3 {
    font-size: 18px;
    margin: 24px 0 8px;
}

.main p {
    margin-bottom: 12px;
}

.main pre {
    background: var(--code-bg);
    padding: 16px;
    border-radius: 6px;
    overflow-x: auto;
    margin-bottom: 16px;
    font-size: 14px;
}

.main code {
    font-size: 0.9em;
    background: var(--code-bg);
    padding: 2px 6px;
    border-radius: 3px;
}

.main pre code {
    background: none;
    padding: 0;
}

.main img {
    max-width: 100%;
    border-radius: 4px;
}

.main blockquote {
    border-left: 3px solid var(--border);
    padding-left: 16px;
    color: var(--muted);
    margin-bottom: 16px;
}

.main ul,
.main ol {
    margin-bottom: 12px;
    padding-left: 24px;
}

.main table {
    border-collapse: collapse;
    width: 100%;
    margin-bottom: 16px;
}

.main th,
.main td {
    border: 1px solid var(--border);
    padding: 8px 12px;
    text-align: left;
}

.main th {
    background: #f6f6f7;
}

.article-meta {
    color: var(--muted);
    font-size: 14px;
    margin-bottom: 24px;
    display: flex;
    gap: 16px;
    align-items: center;
    flex-wrap: wrap;
}

.tag {
    display: inline-block;
    background: var(--tag-bg);
    color: var(--link);
    padding: 2px 10px;
    border-radius: 12px;
    font-size: 12px;
}

.tag:hover {
    background: #d4dbf0;
    text-decoration: none;
}

.article-card {
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 20px;
    margin-bottom: 16px;
    transition: box-shadow 0.15s;
}

.article-card:hover {
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.06);
}

.article-card h3 {
    margin: 0 0 6px 0;
    border: none;
    padding: 0;
}

.article-card p {
    color: var(--muted);
    font-size: 14px;
    margin: 0;
}

.article-card .tags {
    margin-top: 8px;
}

.pagination {
    display: flex;
    gap: 8px;
    margin-top: 32px;
    justify-content: center;
}

.pagination a,
.pagination span {
    padding: 6px 12px;
    border: 1px solid var(--border);
    border-radius: 4px;
    font-size: 14px;
    text-decoration: none;
}

.pagination a:hover {
    border-color: var(--link);
}

.pagination a.active {
    background: var(--link);
    color: #fff;
    border-color: var(--link);
}

.pagination span.ellipsis {
    border: none;
}

.breadcrumb {
    font-size: 14px;
    color: var(--muted);
    margin-bottom: 20px;
}

.category-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
    gap: 16px;
    margin: 24px 0;
}

.category-card {
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 20px;
    display: block;
    color: var(--text);
    transition: box-shadow 0.15s;
}

.category-card:hover {
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.06);
    text-decoration: none;
}

.category-card h3 {
    margin: 0 0 4px 0;
    font-size: 16px;
    border: none;
    padding: 0;
}

.category-card p {
    color: var(--muted);
    font-size: 13px;
    margin: 0;
}

/* ── Right sidebar ── */

.right-sidebar {
    width: 200px;
    flex-shrink: 0;
    position: sticky;
    top: 0;
    height: 100vh;
    overflow-y: auto;
    padding: 24px 16px;
    border-left: 1px solid var(--border);
    font-size: 13px;
}

.right-sidebar h3 {
    font-size: 12px;
    text-transform: uppercase;
    color: var(--muted);
    margin-bottom: 12px;
}

.right-sidebar ul {
    list-style: none;
    padding: 0;
}

.right-sidebar li {
    margin-bottom: 2px;
}

.right-sidebar a {
    color: var(--muted);
    text-decoration: none;
    display: block;
    padding: 2px 6px;
    border-radius: 3px;
    border-left: 2px solid transparent;
}

.right-sidebar a:hover {
    color: var(--link);
    background: #f0f0f4;
    text-decoration: none;
}

.tag-cloud {
    display: flex;
    flex-wrap: wrap;
}

.tag-cloud .tag {
    border: 1px solid var(--border);
    margin: 3px;
    padding: 2px 10px;
    border-radius: 12px;
    white-space: nowrap;
}

.tag-cloud .tag:hover {
    border-color: var(--link);
    text-decoration: none;
}

/* ── Code block copy button ── */

.code-block {
    position: relative;
    margin-bottom: 16px;
}

.code-block pre {
    margin-bottom: 0;
}

.copy-btn {
    position: absolute;
    top: 8px;
    right: 8px;
    background: var(--bg);
    border: 1px solid var(--border);
    border-radius: 4px;
    padding: 4px 10px;
    font-size: 12px;
    cursor: pointer;
    color: var(--muted);
    opacity: 0;
    transition: opacity 0.15s;
}

.code-block:hover .copy-btn {
    opacity: 1;
}

.copy-btn:hover {
    background: #f0f0f4;
    color: var(--text);
}

/* ── Footer ── */

.site-footer {
    margin-top: auto;
    padding: 24px 0 0;
    border-top: 1px solid var(--border);
    text-align: center;
}

.site-footer p {
    font-size: 13px;
    color: var(--muted);
    margin: 0;
}

/* ── Mobile ── */

.mobile-topbar,
.toggle-nav,
.toggle-toc {
    display: none;
}

.overlay {
    display: none;
}

@media (max-width: 768px) {
    .layout {
        flex-direction: column;
    }

    .sidebar,
    .right-sidebar {
        display: none;
        position: fixed;
        top: 0;
        z-index: 100;
        height: 100vh;
        background: #fafafa;
        box-shadow: 2px 0 12px rgba(0, 0, 0, 0.1);
    }

    .sidebar {
        left: 0;
        width: 280px;
    }

    .sidebar.open,
    .right-sidebar.open {
        display: block;
    }

    .right-sidebar {
        right: 0;
        width: 260px;
        border-left: 1px solid var(--border);
    }

    .toggle-nav,
    .toggle-toc {
        display: flex;
        align-items: center;
        justify-content: center;
        gap: 4px;
        background: var(--bg);
        border: 1px solid var(--border);
        border-radius: 6px;
        padding: 6px 10px;
        font-size: 13px;
        cursor: pointer;
        color: var(--text);
        white-space: nowrap;
    }

    .mobile-topbar {
        display: flex;
        align-items: center;
        justify-content: space-between;
        position: fixed;
        top: 0;
        left: 0;
        right: 0;
        z-index: 60;
        height: 44px;
        padding: 0 10px;
        background: var(--bg);
        border-bottom: 1px solid var(--border);
    }

    .topbar-title {
        font-size: 14px;
        font-weight: 600;
        color: var(--text);
        overflow: hidden;
        text-overflow: ellipsis;
        white-space: nowrap;
        margin: 0 4px;
        text-align: center;
        flex: 1;
    }

    .main {
        padding: 60px 16px 32px;
    }

    .overlay {
        display: none;
        position: fixed;
        inset: 0;
        z-index: 99;
        background: rgba(0, 0, 0, 0.3);
    }

    .overlay.show {
        display: block;
    }

    .copy-btn {
        opacity: 1;
    }

    /* 侧边栏打开时在汉堡按钮之上 */
    body.sidebar-open .sidebar,
    body.sidebar-open .right-sidebar {
        z-index: 120;
    }

    /* 侧边栏打开时顶部栏降级，让侧边栏覆盖 */
    body.sidebar-open .mobile-topbar {
        z-index: 40;
    }
}