/* ============================================================
   主题变量
   ============================================================ */
:root {
    --bg-base: #121212;
    --bg-sidebar: #1a1a1a;
    --bg-nav: #1e1e1e;
    --bg-hover: #242424;
    --bg-active: #1a2a3a;
    --bg-subnav-active: #2d2d2d;
    --border: #2a2a2a;
    --text-primary: #f5f5f5;
    --text-secondary: #b0b0b0;
    --text-muted: #9e9e9e;
    --text-content: #a8a8a8;
    --accent: #2196f3;
    --accent-dark: #0b7ad1;
    --header-h: 60px;
    --sidebar-w: 240px;
    --transition: .2s ease;
}

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

html, body {
    height: 100%;
    margin: 0;
    padding: 0;
}

body {
    display: flex;
    flex-direction: column;
    background: var(--bg-base);
    color: var(--text-primary);
    font-family: -apple-system, "Segoe UI", "Microsoft YaHei", sans-serif;
    overflow: hidden;
    -webkit-tap-highlight-color: transparent;
}

::-webkit-scrollbar { width: 6px; height: 6px; }
::-webkit-scrollbar-track { background: #1a1a1a; }
::-webkit-scrollbar-thumb { background: #333; border-radius: 4px; }
::-webkit-scrollbar-thumb:hover { background: #444; }

/* ============================================================
   头部
   ============================================================ */
.page-header {
    display: flex;
    height: var(--header-h);
    border-bottom: 1px solid var(--border);
    flex-shrink: 0;
    background: var(--bg-nav);
    position: relative;
    z-index: 20;
}

.menu-toggle {
    display: none;
    background: transparent;
    border: none;
    color: var(--text-primary);
    font-size: 26px;
    line-height: 1;
    padding: 0 16px;
    cursor: pointer;
    flex-shrink: 0;
    align-items: center;
    justify-content: center;
    touch-action: manipulation;
}
.menu-toggle:active { background: var(--bg-hover); }

.site-logo {
    width: var(--sidebar-w);
    flex-shrink: 0;
    background: var(--bg-sidebar);
    display: flex;
    align-items: center;
    padding: 0 16px;
    font-size: 17px;
    font-weight: bold;
    color: var(--text-primary);
    border-right: 1px solid var(--border);
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    transition: width var(--transition);
}

.sub-nav-bar {
    flex: 1;
    background: var(--bg-nav);
    display: flex;
    align-items: center;
    padding: 0 6px;
    gap: 2px;
    overflow-x: auto;
    overflow-y: hidden;
    scrollbar-width: none;
    -webkit-overflow-scrolling: touch;
    scroll-behavior: smooth;
    white-space: nowrap;
}
.sub-nav-bar::-webkit-scrollbar { display: none; }

.sub-nav-bar button {
    background: transparent;
    border: none;
    border-bottom: 2px solid transparent;
    color: var(--text-muted);
    font-size: 15px;
    font-family: inherit;
    padding: 10px 14px;
    cursor: pointer;
    white-space: nowrap;
    transition: color var(--transition), background var(--transition), border-color var(--transition);
    flex-shrink: 0;
    touch-action: manipulation;
    border-radius: 0;
}
.sub-nav-bar button:hover {
    color: var(--text-primary);
    background: var(--bg-hover);
}
.sub-nav-bar button[aria-selected="true"] {
    color: #fff;
    background: var(--bg-subnav-active);
    border-bottom-color: var(--accent);
}
.sub-nav-bar button:focus-visible {
    outline: 2px solid var(--accent);
    outline-offset: -2px;
}

.placeholder {
    color: #666;
    font-size: 14px;
    padding: 0 12px;
}

/* ============================================================
   主体
   ============================================================ */
.page-body {
    flex: 1;
    display: flex;
    min-height: 0;
    position: relative;
}

.main-sidebar {
    width: var(--sidebar-w);
    flex-shrink: 0;
    background: var(--bg-sidebar);
    padding-top: 8px;
    border-right: 1px solid var(--border);
    overflow-y: auto;
    -webkit-overflow-scrolling: touch;
    transition: transform var(--transition);
}

.main-sidebar .main-btn {
    display: block;
    width: 100%;
    text-align: left;
    background: none;
    border: none;
    border-left: 4px solid transparent;
    padding: 15px 20px;
    color: var(--text-secondary);
    font-size: 16px;
    font-family: inherit;
    cursor: pointer;
    transition: background var(--transition), color var(--transition), border-color var(--transition);
    touch-action: manipulation;
    border-radius: 0;
    margin-right: 4px;
    position: relative;
}
.main-sidebar .main-btn:hover {
    background: var(--bg-hover);
    color: var(--text-primary);
}
.main-sidebar .main-btn[aria-current="page"] {
    background: var(--bg-active);
    color: #fff;
    border-left-color: var(--accent);
}
.main-sidebar .main-btn:focus-visible {
    outline: 2px solid var(--accent);
    outline-offset: -2px;
}

.sub-list {
    display: none;
    background: #171717;
    padding: 4px 0;
    border-radius: 0;
    margin-bottom: 4px;
}
.sub-list.expanded { display: block; }

.sub-list button {
    display: block;
    width: 100%;
    text-align: left;
    background: none;
    border: none;
    border-left: 4px solid transparent;
    padding: 12px 20px 12px 40px;
    color: var(--text-muted);
    font-size: 15px;
    font-family: inherit;
    cursor: pointer;
    transition: background var(--transition), color var(--transition), border-color var(--transition);
    touch-action: manipulation;
    border-radius: 0;
    margin-right: 4px;
}
.sub-list button:hover {
    background: var(--bg-hover);
    color: var(--text-primary);
}
.sub-list button[aria-selected="true"] {
    color: #fff;
    background: var(--bg-active);
    border-left-color: var(--accent);
}
.sub-list button:focus-visible {
    outline: 2px solid var(--accent);
    outline-offset: -2px;
}

/* ============================================================
   内容区（HTML 排版）
   ============================================================ */
.main-content {
    flex: 1;
    min-width: 0;
    padding: 28px 32px;
    background: var(--bg-base);
    color: var(--text-content);
    overflow-y: auto;
    -webkit-overflow-scrolling: touch;
    line-height: 1.7;
    scroll-behavior: smooth;
    outline: none;
}
.main-content:focus { outline: none; }

.main-content h1,
.main-content h2,
.main-content h3,
.main-content h4 {
    color: var(--text-primary);
    margin: 20px 0 12px;
    line-height: 1.3;
}
.main-content h1 { font-size: 24px; }
.main-content h2 { font-size: 22px; }
.main-content h3 { font-size: 18px; }
.main-content h4 { font-size: 16px; }
.main-content h1:first-child,
.main-content h2:first-child,
.main-content h3:first-child { margin-top: 0; }

.main-content p {
    color: var(--text-content);
    margin-bottom: 10px;
}
.main-content ul,
.main-content ol {
    margin: 10px 0 14px 24px;
    color: var(--text-content);
}
.main-content li { margin-bottom: 4px; }

.main-content a {
    color: var(--accent);
    text-decoration: none;
}
.main-content a:hover { text-decoration: underline; }

.main-content code {
    background: #1e1e1e;
    border: 1px solid var(--border);
    padding: 2px 6px;
    font-size: 13px;
    font-family: Consolas, Monaco, monospace;
    color: #e0e0e0;
}
.main-content pre {
    background: #1a1a1a;
    border: 1px solid var(--border);
    padding: 14px 16px;
    overflow-x: auto;
    margin: 12px 0;
}
.main-content pre code {
    background: none;
    border: none;
    padding: 0;
}

.main-content blockquote {
    border-left: 3px solid var(--accent);
    background: #1a1a1a;
    padding: 10px 16px;
    margin: 12px 0;
    color: var(--text-muted);
}

.main-content table {
    border-collapse: collapse;
    width: 100%;
    margin: 12px 0;
    font-size: 14px;
}
.main-content th,
.main-content td {
    border: 1px solid var(--border);
    padding: 8px 12px;
    text-align: left;
}
.main-content th {
    background: #1e1e1e;
    color: var(--text-primary);
}

.main-content hr {
    border: none;
    border-top: 1px solid var(--border);
    margin: 20px 0;
}

.main-content img {
    max-width: 100%;
    height: auto;
    display: block;
    margin: 12px 0;
}

.loading {
    color: var(--text-muted);
    font-size: 14px;
    padding: 20px 0;
}

/* ============================================================
   图片放大遮罩
   ============================================================ */
.img-zoom-overlay {
    position: fixed;
    inset: 0;
    background: rgba(0,0,0,0.92);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 999;
    cursor: zoom-out;
    padding: 20px;
}
.img-zoom-overlay img {
    max-width: 95vw;
    max-height: 95vh;
    object-fit: contain;
}

/* ============================================================
   侧边栏遮罩
   ============================================================ */
.sidebar-overlay {
    display: none;
    position: fixed;
    inset: 0;
    background: rgba(0,0,0,0.6);
    z-index: 90;
    opacity: 0;
    transition: opacity var(--transition);
    pointer-events: none;
}
.sidebar-overlay.active {
    display: block;
    opacity: 1;
    pointer-events: auto;
}

/* ============================================================
   响应式：手机
   ============================================================ */
@media (max-width: 720px) {
    :root { --header-h: 56px; }

    .menu-toggle { display: flex; }

    .site-logo {
        width: auto;
        flex: 1;
        border-right: none;
        padding-left: 0;
        font-size: 16px;
    }

    .sub-nav-bar { display: none; }

    .main-sidebar {
        position: fixed;
        top: var(--header-h);
        bottom: 0;
        left: 0;
        z-index: 100;
        width: 280px;
        max-width: 85vw;
        transform: translateX(-100%);
        transition: transform 0.28s cubic-bezier(0.4, 0, 0.2, 1);
        box-shadow: 4px 0 20px rgba(0,0,0,0.7);
        border-right: none;
        border-radius: 0;
        padding-top: 12px;
        background: #1c1c1c;
        overflow-y: auto;
    }
    .main-sidebar.open { transform: translateX(0); }

    .main-sidebar .main-btn {
        padding: 16px 22px;
        font-size: 17px;
        border-left-width: 5px;
        border-radius: 0;
        margin-right: 8px;
    }

    .sub-list button {
        padding: 14px 22px 14px 42px;
        font-size: 16px;
        border-radius: 0;
        margin-right: 8px;
    }

    .main-content {
        padding: 20px 16px;
        font-size: 15px;
    }
    .main-content h1 { font-size: 20px; }
    .main-content h2 { font-size: 20px; }
    .main-content h3 { font-size: 17px; }

    .sidebar-overlay { display: block; }
}

@media (max-width: 400px) {
    .site-logo { font-size: 14px; padding-right: 4px; }
    .main-sidebar { width: 260px; }
}

@media (prefers-reduced-motion: reduce) {
    * { transition: none !important; scroll-behavior: auto !important; }
    .main-sidebar { transition: none; }
}

body.no-scroll { overflow: hidden; }