/* ============================================
   通用科普文章样式 v2.2 - 纸感阅读版
   2026-10-18：按站长定调"文章=白纸黑字"——默认暖白纸底+墨色字+宋体正文，
   点缀色改沉稳墨蓝（去霓虹紫/渐变/光晕的科技感）；深色为夜间切换项
   ============================================ */
:root {
    --bg-primary: #f7f4ee;            /* 暖纸底 */
    --bg-secondary: #fffdf8;          /* 纸面卡片 */
    --bg-tertiary: #efece3;           /* 纸面沉一档 */
    --text-primary: #2a2a28;          /* 墨色 */
    --text-secondary: #3f3f3c;
    --text-muted: #8a8578;
    --color-accent: #33507e;          /* 墨蓝（去霓虹） */
    --color-accent-light: #48699e;
    --color-accent-dark: #274064;
    --color-success: #3f7d5c;
    --color-warning: #a86a28;
    --color-danger: #a54242;
    --color-info: #33507e;
    --gradient-primary: linear-gradient(135deg, #33507e 0%, #48699e 100%);
    --shadow-sm: 0 1px 2px 0 rgba(42, 42, 40, 0.06);
    --shadow-md: 0 4px 8px -2px rgba(42, 42, 40, 0.08);
    --shadow-lg: 0 10px 20px -6px rgba(42, 42, 40, 0.10);
    --border-color: #e4e0d5;
    --border-radius-sm: 6px;
    --border-radius-md: 10px;
    --border-radius-lg: 14px;
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    --transition-fast: 0.15s ease;
    --transition-base: 0.3s ease;
}

/* 夜间阅读模式（🌙 切换）：暖灰夜灯，非站点的霓虹深紫 */
[data-theme="dark"] {
    --bg-primary: #211f1c;
    --bg-secondary: #2a2724;
    --bg-tertiary: #35322d;
    --text-primary: #e8e4da;
    --text-secondary: #cfcabd;
    --text-muted: #8f8a7e;
    --color-accent: #8fa8cc;
    --color-accent-light: #a4bbdb;
    --color-accent-dark: #7490b8;
    --border-color: #3b3833;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 8px -2px rgba(0, 0, 0, 0.35);
    --shadow-lg: 0 10px 20px -6px rgba(0, 0, 0, 0.4);
}

* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; font-size: 16px; }
body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "PingFang SC", "Microsoft YaHei", sans-serif;
    line-height: 1.7; color: var(--text-primary); background-color: var(--bg-primary);
    transition: background-color var(--transition-base), color var(--transition-base);
}

.progress-bar {
    position: fixed; top: 0; left: 0; width: 0%; height: 3px;
    background: var(--color-accent); z-index: 9999;
    transition: width 0.1s ease;
}

.navbar {
    position: sticky; top: 0; background-color: var(--bg-primary);
    border-bottom: 1px solid var(--border-color); z-index: 1000;
    box-shadow: var(--shadow-sm);
}
.nav-container {
    max-width: 1200px; margin: 0 auto; padding: var(--spacing-sm) var(--spacing-md);
    display: flex; justify-content: space-between; align-items: center;
}
.nav-logo {
    font-size: 1.2rem; font-weight: 700; color: var(--text-primary);
    text-decoration: none !important;
}
.nav-menu { display: flex; gap: var(--spacing-sm); }
.nav-toggle, .theme-toggle {
    background: transparent; border: 1px solid var(--border-color);
    padding: 0.5rem 1rem; border-radius: var(--border-radius-sm);
    cursor: pointer; font-size: 1.2rem; transition: all var(--transition-base);
}
.nav-toggle:hover, .theme-toggle:hover {
    background-color: var(--bg-secondary); transform: translateY(-2px);
}

.sidebar {
    position: fixed; left: -300px; top: 60px; width: 280px;
    height: calc(100vh - 60px); background-color: var(--bg-secondary);
    border-right: 1px solid var(--border-color); padding: var(--spacing-md);
    overflow-y: auto; transition: left var(--transition-base); z-index: 999;
    box-shadow: var(--shadow-lg);
}
.sidebar.active { left: 0; }
.sidebar-content h3 { margin-bottom: var(--spacing-md); color: var(--text-primary); font-size: 1.1rem; }
.catalog { list-style: none; }
.catalog li { margin-bottom: var(--spacing-sm); }
.catalog a {
    display: block; color: var(--text-secondary); text-decoration: none;
    padding: 0.5rem 0.75rem; border-radius: var(--border-radius-sm);
    transition: all var(--transition-fast); font-size: 0.95rem;
}
.catalog a:hover { color: var(--color-accent); background-color: var(--bg-tertiary); padding-left: 1rem; }
.catalog a.active { color: var(--color-accent); background-color: var(--bg-tertiary); font-weight: 600; border-left: 3px solid var(--color-accent); }

/* 正文列宽：约 42 个汉字/行（中文长文规范 35-45 字） */
.main-content { max-width: 720px; margin: 0 auto; padding: var(--spacing-xl) var(--spacing-md); }

/* 正文：宋体书卷气 + 阅读行距（UI 仍为无衬线） */
.markdown-body {
    line-height: 1.85; color: var(--text-secondary); font-size: 1.05rem;
    font-family: Georgia, "Nimbus Roman", "Songti SC", "Noto Serif CJK SC", "Source Han Serif SC", "SimSun", serif;
}

/* 标题区：去渐变横幅，改用卡片式克制排版 */
.article-header {
    text-align: left; margin-bottom: var(--spacing-xl);
    padding: var(--spacing-lg) var(--spacing-lg);
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-lg); color: var(--text-primary);
    box-shadow: var(--shadow-md);
}
.article-title {
    font-size: 2rem; font-weight: 800; margin-bottom: var(--spacing-sm);
    line-height: 1.3; text-shadow: none;
}
.article-subtitle { font-size: 1.1rem; color: var(--text-muted); margin-bottom: var(--spacing-md); }
.article-meta {
    display: flex; gap: var(--spacing-md);
    flex-wrap: wrap; margin-bottom: var(--spacing-md); font-size: 0.9rem;
    color: var(--text-muted);
}
.meta-item { display: flex; align-items: center; gap: 0.25rem; }
.article-tags { display: flex; gap: 0.5rem; flex-wrap: wrap; margin-bottom: var(--spacing-md); }
.tag {
    display: inline-block; padding: 0.25rem 0.8rem;
    background: rgba(99, 102, 241, 0.15); border: 1px solid var(--border-color);
    border-radius: 20px; font-size: 0.82rem; color: var(--text-secondary);
}
.article-actions { display: flex; gap: var(--spacing-sm); flex-wrap: wrap; }
.btn-action {
    background-color: transparent; border: 1px solid var(--border-color);
    color: var(--text-secondary); padding: 0.5rem 1.3rem; border-radius: var(--border-radius-md);
    cursor: pointer; font-size: 0.92rem; font-weight: 600;
    transition: all var(--transition-base);
}
.btn-action:hover { border-color: var(--color-accent); color: var(--color-accent-light); transform: translateY(-2px); }
.btn-action.active { background: rgba(99, 102, 241, 0.15); border-color: var(--color-accent); color: var(--color-accent-light); }

/* ============================================
   Markdown 正文样式 (核心部分)
   ============================================ */
.markdown-body {
    line-height: 1.8; color: var(--text-secondary); font-size: 1.05rem;
}

.markdown-body > *:first-child { margin-top: 0; }
.markdown-body > *:last-child { margin-bottom: 0; }

/* 标题层级：正文 h1 降级防撞文章主标；h2 带主题色条 */
.markdown-body h1, .markdown-body h2, .markdown-body h3, .markdown-body h4,
.markdown-body h5, .markdown-body h6 {
    color: var(--text-primary); font-weight: 700; line-height: 1.4;
    margin-top: 2em; margin-bottom: 0.8em;
}
.markdown-body h1 { font-size: 1.75rem; border-bottom: 1px solid var(--border-color); padding-bottom: 0.3em; }
.markdown-body h2 { font-size: 1.5rem; padding-bottom: 0.3em; border-bottom: 1px solid var(--border-color); }
.markdown-body h3 { font-size: 1.25rem; }
.markdown-body h4 { font-size: 1.1rem; color: var(--text-primary); }
.markdown-body h5 { font-size: 1rem; color: var(--text-secondary); font-weight: 600; }
.markdown-body h6 { font-size: 0.9rem; color: var(--text-muted); }
.markdown-body h2::before {
    content: ""; display: inline-block; width: 4px; height: 1em;
    background: var(--gradient-primary); border-radius: 2px;
    margin-right: 0.5em; vertical-align: -0.1em;
}

/* 段落：两端对齐 + 中西文间距微调 */
.markdown-body { text-autospace: ideograph-alpha ideograph-numeric; }
.markdown-body p { margin-bottom: 1.1em; text-align: justify; }

/* 链接 */
.markdown-body a {
    color: var(--color-accent-light); text-decoration: none;
    border-bottom: 1px solid transparent; transition: all var(--transition-fast);
}
.markdown-body a:hover { color: var(--color-accent); border-bottom-color: var(--color-accent); }

/* 粗体和斜体 */
.markdown-body strong { font-weight: 700; color: var(--text-primary); }
.markdown-body em { font-style: italic; }

/* 列表 */
.markdown-body ul, .markdown-body ol { margin-bottom: 1.2em; padding-left: 2em; }
.markdown-body li { margin-bottom: 0.5em; line-height: 1.7; }
.markdown-body li > ul, .markdown-body li > ol { margin-top: 0.5em; margin-bottom: 0.5em; }
.markdown-body ul { list-style-type: disc; }
.markdown-body ol { list-style-type: decimal; }
.markdown-body li::marker { color: var(--color-accent); font-weight: 600; }

/* 引用块：细左线 + 淡色底，不再把 strong 染成主题色 */
.markdown-body blockquote {
    margin: 1.5em 0; padding: 1em 1.5em;
    border-left: 3px solid var(--color-accent);
    background: rgba(99, 102, 241, 0.08);
    border-radius: 0 var(--border-radius-md) var(--border-radius-md) 0;
    color: var(--text-secondary);
}
.markdown-body blockquote p:last-child { margin-bottom: 0; }
.markdown-body blockquote strong { color: var(--text-primary); }

/* 代码：纸面代码卡——两种主题下都保持浅色纸底（hljs 用 light 配色） */
.markdown-body code {
    padding: 0.15em 0.4em; margin: 0;
    font-size: 0.875em; font-family: ui-monospace, "Cascadia Code", Consolas, "Courier New", monospace;
    background-color: #f0ede4; border-radius: 4px;
    color: #8a4a3a;
}
.markdown-body pre {
    margin: 1.5em 0; padding: 1.2em;
    background-color: #f7f5ef;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-md);
    overflow-x: auto; line-height: 1.6;
}
[data-theme="dark"] .markdown-body pre { background-color: #f7f5ef; }
.markdown-body pre code {
    padding: 0; margin: 0; font-size: 0.9em;
    background: transparent; border: none; border-radius: 0;
    color: #24292e;
}

/* 表格：去渐变紫表头，加横向滚动包裹容器 */
.markdown-body table {
    width: 100%; margin: 1.5em 0; border-collapse: collapse;
    background-color: var(--bg-secondary);
    border-radius: var(--border-radius-md); overflow: hidden;
    box-shadow: var(--shadow-sm);
}
.markdown-body thead { background: var(--bg-tertiary); color: var(--text-primary); }
.markdown-body thead th { border-bottom: 2px solid var(--color-accent); }
.markdown-body th, .markdown-body td {
    padding: 0.7em 0.9em; text-align: left; border-bottom: 1px solid var(--border-color);
}
.markdown-body th { font-weight: 600; }
.markdown-body tbody tr:last-child td { border-bottom: none; }
.markdown-body tbody tr { transition: background-color var(--transition-fast); }
.markdown-body tbody tr:hover { background-color: var(--bg-tertiary); }
.table-wrap { overflow-x: auto; -webkit-overflow-scrolling: touch; }
.table-wrap table { min-width: 600px; }

/* 图片与图注（figcaption 由 script.js 从 alt 生成） */
.markdown-body img {
    max-width: 100%; height: auto; border-radius: var(--border-radius-md);
    margin: 1.5em 0; box-shadow: var(--shadow-md);
    display: block; margin-left: auto; margin-right: auto;
}
.markdown-body figure { margin: 1.5em auto; text-align: center; }
.markdown-body figcaption { font-size: 0.85rem; color: var(--text-muted); margin-top: 0.5em; }

/* 参考文献区 */
.references-section {
    margin-top: var(--spacing-xl); padding: var(--spacing-lg);
    border: 1px solid var(--border-color); border-radius: var(--border-radius-md);
    background: var(--bg-secondary);
}
.references-section > h2 { font-size: 1.25rem; margin-bottom: var(--spacing-sm); color: var(--text-primary); }
.references-section .markdown-body { font-size: 0.92rem; }

/* 上一篇/下一篇 */
.article-nav {
    display: grid; grid-template-columns: 1fr 1fr; gap: 1rem; margin-top: var(--spacing-xl);
}
.article-nav .nav-card {
    display: flex; flex-direction: column; gap: 0.3rem;
    padding: 1rem 1.2rem; border: 1px solid var(--border-color);
    border-radius: var(--border-radius-md); background: var(--bg-secondary);
    text-decoration: none !important; transition: border-color var(--transition-fast), transform var(--transition-fast);
}
.article-nav .nav-card:hover { border-color: var(--color-accent); transform: translateY(-2px); }
.article-nav .nav-card.next { text-align: right; }
.article-nav .nav-label { font-size: 0.78rem; color: var(--text-muted); }
.article-nav .nav-title { font-size: 0.95rem; font-weight: 600; color: var(--text-primary); }

/* 分隔线 */
.markdown-body hr {
    height: 2px; margin: 2em 0; padding: 0;
    background: var(--gradient-primary); border: none; border-radius: 1px;
}

/* 图片 */
.markdown-body img {
    max-width: 100%; height: auto; border-radius: var(--border-radius-md);
    margin: 1.5em 0; box-shadow: var(--shadow-md);
    display: block; margin-left: auto; margin-right: auto;
}

/* 删除线 */
.markdown-body del { text-decoration: line-through; color: var(--text-muted); }

/* 任务列表 */
.markdown-body input[type="checkbox"] {
    margin-right: 0.5em; accent-color: var(--color-accent);
}

/* 数学公式容器（如果使用KaTeX等） */
.markdown-body .katex-display { margin: 1.5em 0; overflow-x: auto; }

/* ============================================
   互动区域样式
   ============================================ */
.interaction-section {
    background: var(--bg-secondary);
    padding: var(--spacing-lg); border-radius: var(--border-radius-lg);
    margin-top: var(--spacing-xl); border: 1px solid var(--border-color);
}
.interaction-section h2 { border: none; }

.comment-section {
    background-color: var(--bg-secondary); padding: var(--spacing-lg);
    border-radius: var(--border-radius-lg); margin: var(--spacing-md) 0;
}
.comment-form { display: flex; flex-direction: column; gap: var(--spacing-sm); margin-bottom: var(--spacing-md); }
.comment-form input, .comment-form textarea {
    padding: var(--spacing-sm); border: 2px solid var(--border-color);
    border-radius: var(--border-radius-sm); background-color: var(--bg-primary);
    color: var(--text-primary); font-family: inherit;
}
.comment-form input:focus, .comment-form textarea:focus {
    outline: none; border-color: var(--color-accent);
    box-shadow: 0 0 0 3px rgba(79, 70, 229, 0.1);
}
.comment-form textarea { resize: vertical; min-height: 80px; }
.btn-submit {
    background: var(--gradient-primary); color: white; border: none;
    padding: var(--spacing-sm) var(--spacing-md); border-radius: var(--border-radius-md);
    cursor: pointer; font-weight: 600; font-size: 1rem;
    transition: all var(--transition-base);
}
.btn-submit:hover { transform: translateY(-2px); box-shadow: var(--shadow-lg); }

.help-resources {
    background-color: rgba(239, 68, 68, 0.1); border: 2px solid var(--color-danger);
    padding: var(--spacing-md); border-radius: var(--border-radius-md); margin: var(--spacing-md) 0;
}
.help-resources h3 { color: var(--color-danger); margin-bottom: var(--spacing-sm); }

.closing-message {
    text-align: center; padding: var(--spacing-lg) var(--spacing-md);
    color: var(--text-muted); font-size: 0.95rem;
    border-top: 1px solid var(--border-color);
    border-radius: 0; margin-top: var(--spacing-xl); background: none;
}
.closing-title { font-size: 1.1rem; font-weight: 700; margin-bottom: var(--spacing-xs); color: var(--text-secondary); }

.back-to-top {
    position: fixed; bottom: 30px; right: 30px; width: 50px; height: 50px;
    background: var(--gradient-primary); color: white; border: none;
    border-radius: 50%; font-size: 1.5rem; cursor: pointer;
    opacity: 0; visibility: hidden; transition: all var(--transition-base);
    box-shadow: var(--shadow-lg); z-index: 998;
}
.back-to-top.visible { opacity: 1; visibility: visible; }
.back-to-top:hover { transform: translateY(-5px); box-shadow: 0 20px 25px -5px rgba(0,0,0,0.3); }

.back-to-kepu {
    position: fixed; bottom: 96px; left: 20px; z-index: 998;   /* 避开左上角 logo 与右下返回顶部 */
    display: flex; align-items: center; gap: 6px;
    padding: 10px 16px; background: var(--bg-secondary);
    color: var(--text-primary) !important; text-decoration: none !important;
    border: 1px solid var(--border-color);
    border-radius: 24px; font-size: 14px; font-weight: 600;
    box-shadow: var(--shadow-md);
    transition: all 0.3s ease;
}
.back-to-kepu:hover { border-color: var(--color-accent); color: var(--color-accent) !important; transform: translateY(-2px); }

.modal { display: none; position: fixed; z-index: 10000; left: 0; top: 0; width: 100%; height: 100%; background-color: rgba(0, 0, 0, 0.5); backdrop-filter: blur(5px); }
.modal.active { display: flex; justify-content: center; align-items: center; animation: fadeIn 0.3s ease; }
@keyframes fadeIn { from { opacity: 0; } to { opacity: 1; } }

.modal-content {
    background-color: var(--bg-primary); padding: var(--spacing-xl);
    border-radius: var(--border-radius-lg); max-width: 500px; width: 90%;
    position: relative; box-shadow: 0 20px 25px -5px rgba(0,0,0,0.3);
    animation: slideDown 0.3s ease;
}
@keyframes slideDown { from { transform: translateY(-50px); opacity: 0; } to { transform: translateY(0); opacity: 1; } }

.close { position: absolute; top: 10px; right: 20px; font-size: 2rem; color: var(--text-secondary); cursor: pointer; transition: color var(--transition-fast); }
.close:hover { color: var(--color-danger); }
.modal-content h3 { margin-bottom: var(--spacing-md); text-align: center; }
.share-buttons { display: grid; grid-template-columns: repeat(2, 1fr); gap: var(--spacing-sm); }
.share-btn {
    padding: var(--spacing-md); border: 2px solid var(--border-color);
    background-color: var(--bg-secondary); color: var(--text-primary);
    border-radius: var(--border-radius-md); cursor: pointer; font-size: 1rem;
    font-weight: 600; transition: all var(--transition-base);
}
.share-btn:hover { background-color: var(--bg-tertiary); transform: translateY(-2px); box-shadow: var(--shadow-md); }

.comment-item {
    background-color: var(--bg-tertiary); padding: var(--spacing-md);
    border-radius: var(--border-radius-md); margin-bottom: var(--spacing-sm);
    animation: slideIn 0.3s ease;
}
@keyframes slideIn { from { opacity: 0; transform: translateX(-20px); } to { opacity: 1; transform: translateX(0); } }
.comment-header { display: flex; justify-content: space-between; margin-bottom: var(--spacing-xs); }
.comment-name { font-weight: 600; color: var(--color-accent); }
.comment-time { font-size: 0.85rem; color: var(--text-muted); }
.comment-content { color: var(--text-secondary); line-height: 1.6; }

/* 目录层级缩进（toc-h2/h3/h4 类名由 script.js generateTOC 输出） */
.catalog li.toc-h3 a { padding-left: 1.5rem; }
.catalog li.toc-h4 a { padding-left: 2.25rem; font-size: 0.88rem; }

/* 桌面端：目录常驻左侧（不再是藏死的抽屉） */
@media (min-width: 1024px) {
    .sidebar {
        left: 0; top: 61px; box-shadow: none;
        background: transparent; border-right: none; width: 260px;
    }
    .sidebar-content {
        background: var(--bg-secondary); border: 1px solid var(--border-color);
        border-radius: var(--border-radius-md); padding: var(--spacing-md);
        position: sticky; top: 81px; max-height: calc(100vh - 110px); overflow-y: auto;
    }
    .nav-toggle { display: none; }
    .main-content { margin-left: 280px; max-width: 720px; }
}

@media (max-width: 768px) {
    html { font-size: 14px; }
    .article-title { font-size: 1.5rem; }
    .article-subtitle { font-size: 1rem; }
    .article-meta { gap: var(--spacing-xs); }
    .markdown-body h1 { font-size: 1.5rem; }
    .markdown-body h2 { font-size: 1.3rem; }
    .markdown-body table { font-size: 0.85rem; }
    .markdown-body th, .markdown-body td { padding: var(--spacing-xs); }
    .article-nav { grid-template-columns: 1fr; }
    .back-to-top { bottom: 20px; right: 20px; width: 45px; height: 45px; }
    .back-to-kepu { padding: 8px 12px; font-size: 13px; bottom: 84px; left: 14px; }
    .share-buttons { grid-template-columns: 1fr; }
}

@media (max-width: 480px) {
    .main-content { padding: var(--spacing-md) var(--spacing-sm); }
    .article-header { padding: var(--spacing-md); }
}

@media print {
    .navbar, .sidebar, .back-to-top, .progress-bar,
    .article-actions, .comment-section, .back-to-kepu { display: none !important; }
    .main-content { max-width: 100%; padding: 0; }
    .markdown-body { color: #000; }
}

::-webkit-scrollbar { width: 10px; height: 10px; }
::-webkit-scrollbar-track { background: var(--bg-tertiary); }
::-webkit-scrollbar-thumb { background: #b8b2a2; border-radius: 5px; }
::-webkit-scrollbar-thumb:hover { background: #a09a89; }

::selection { background-color: #d8e0ee; color: var(--text-primary); }
::-moz-selection { background-color: #d8e0ee; color: var(--text-primary); }

/* hljs 代码高亮：统一浅色纸面配色（两种阅读主题一致） */
.hljs { background: transparent !important; }