/* ========== CSS 变量（浅色主题默认值） ========== */
:root {
    --bg-primary: #ffffff;
    --bg-secondary: #f6f8fa;
    --text-primary: #1f2328;
    --text-secondary: #57606a;
    --border-color: #e1e4e8;
    --code-bg: #f8fafc;
    --pre-bg: #1e1e1e;
    --pre-text: #d4d4d4;
    --link-color: #0969da;
    --link-hover-bg: #f0f4fa;
    --table-header-bg: #f6f8fa;
    --badge-bg: #e9ecef;
    --note-bg: #eef5ff;
    --tip-bg: #e6f7ec;
    --warning-bg: #fff3e3;
    --sidebar-bg: #ffffff;
    --main-bg: #ffffff;
}

/* ========== 全局重置 ========== */
* { margin: 0; padding: 0; box-sizing: border-box; }

/* ========== Body ========== */
body {
    background: var(--bg-secondary);
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Noto Sans', 'Inter', system-ui, Helvetica, Arial, sans-serif;
    line-height: 1.6;
    color: var(--text-primary);
    transition: background 0.2s, color 0.2s;
}

/* ========== 顶部导航栏 ========== */
.topbar {
    height: 56px;
    background: var(--bg-primary);
    border-bottom: 1px solid var(--border-color);
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 1.5rem;
    position: sticky;
    top: 0;
    z-index: 100;
    box-shadow: 0 1px 3px rgba(0,0,0,0.06);
}
.topbar .brand {
    font-weight: 600;
    font-size: 1.1rem;
    color: var(--text-primary);
    display: flex;
    align-items: center;
    gap: 0.5rem;
}
.topbar .brand .badge {
    background: var(--badge-bg);
    color: var(--text-secondary);
    padding: 0.15rem 0.6rem;
    border-radius: 20px;
    font-size: 0.7rem;
    font-family: monospace;
}
.topbar .actions {
    display: flex;
    align-items: center;
    gap: 1rem;
}
.topbar button,
.topbar select {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    color: var(--text-primary);
    padding: 0.4rem 0.8rem;
    border-radius: 8px;
    font-size: 0.85rem;
    cursor: pointer;
    transition: background 0.2s;
}
.topbar button:hover,
.topbar select:hover {
    background: var(--border-color);
}

/* ========== 主布局 ========== */
.layout {
    display: flex;
    width: 100%;
    min-height: calc(100vh - 56px);
}

/* ========== 侧边栏 ========== */
.sidebar {
    width: 270px;
    flex-shrink: 0;
    background: var(--sidebar-bg);
    border-right: 1px solid var(--border-color);
    padding: 1.5rem 0;
    overflow-y: auto;
    position: sticky;
    top: 56px;
    height: calc(100vh - 56px);
}
.sidebar .toc { padding: 0 1rem; }
.sidebar .toc h3 {
    font-size: 1rem;
    margin: 0 0 1rem;
    padding-left: 0.5rem;
    color: var(--link-color);
    border-left: 3px solid var(--link-color);
}
.sidebar .toc ul { list-style: none; padding-left: 0; }
.sidebar .toc li { margin: 0.4rem 0; }
.sidebar .toc a {
    text-decoration: none;
    color: var(--text-primary);
    font-size: 0.85rem;
    display: block;
    padding: 0.3rem 0.5rem;
    border-radius: 6px;
    transition: all 0.2s;
}
.sidebar .toc a:hover,
.sidebar .toc a.active {
    background-color: var(--link-hover-bg);
    color: var(--link-color);
}
.sidebar .toc .level-2 { margin-left: 1rem; }

/* ========== 侧边栏滚动条（浅色） ========== */
.sidebar::-webkit-scrollbar {
    width: 6px;
}
.sidebar::-webkit-scrollbar-track {
    background: transparent;
}
.sidebar::-webkit-scrollbar-thumb {
    background: #c1c1c1;
    border-radius: 3px;
}
.sidebar::-webkit-scrollbar-thumb:hover {
    background: #a0a0a0;
}

/* ========== 主内容区 ========== */
.main-content {
    flex: 1;
    min-width: 0;
    background: var(--main-bg);
    padding: 2rem 2.5rem;
    overflow-x: auto;
}

/* ========== 响应式 ========== */
@media (max-width: 768px) {
    .layout {
        flex-direction: column;
    }
    .sidebar {
        position: static;
        width: 100%;
        height: auto;
        border-right: none;
        border-bottom: 1px solid var(--border-color);
        padding: 1rem;
    }
    .main-content {
        padding: 1.5rem;
    }
}