2026-02-21 10:04:47 +08:00
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<template>
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<div class="what-is-dom-demo">
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<div class="demo-header">
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<span class="title">HTML → DOM 树</span>
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<span class="subtitle">浏览器如何理解你写的 HTML</span>
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</div>
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<div class="demo-body">
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<div class="html-panel">
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<div class="panel-title">你写的 HTML 代码</div>
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<div class="code-display">
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<div
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v-for="(line, i) in htmlLines"
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:key="i"
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:class="['code-line', { highlighted: highlightedTag === line.tag }]"
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@mouseenter="highlightedTag = line.tag"
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@mouseleave="highlightedTag = ''"
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>
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<span class="line-num">{{ i + 1 }}</span>
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<span class="line-code" :style="{ paddingLeft: line.indent * 12 + 'px' }">{{ line.text }}</span>
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</div>
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</div>
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</div>
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<div class="arrow-col">
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<div class="arrow-label">浏览器解析</div>
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<div class="arrow-icon">→</div>
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</div>
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<div class="tree-panel">
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<div class="panel-title">浏览器生成的 DOM 树</div>
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<div class="tree-display">
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<div
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v-for="node in treeNodes"
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:key="node.id"
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:class="['tree-node', { highlighted: highlightedTag === node.tag }]"
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:style="{ marginLeft: node.depth * 20 + 'px' }"
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@mouseenter="highlightedTag = node.tag"
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@mouseleave="highlightedTag = ''"
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>
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2026-02-24 00:18:09 +08:00
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<span v-if="node.depth > 0" class="connector">└─</span>
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2026-02-21 10:04:47 +08:00
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<span class="node-tag">{{ node.label }}</span>
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<span v-if="node.text" class="node-text">"{{ node.text }}"</span>
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</div>
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</div>
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</div>
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</div>
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<div class="dom-explain">
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<div class="explain-item">
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<span class="explain-icon">📄</span>
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<div class="explain-content">
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<strong>节点（Node）</strong>
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<span>DOM 树上的每一个方块就是一个节点。每个 HTML 标签（如 <code><h1></code>、<code><p></code>）都对应一个节点。</span>
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</div>
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</div>
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<div class="explain-item">
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<span class="explain-icon">🌳</span>
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<div class="explain-content">
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<strong>父子关系</strong>
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<span>标签嵌套在另一个标签里面，在 DOM 树上就是父节点和子节点的关系。<code><body></code> 里包含 <code><h1></code>，所以 body 是 h1 的父节点。</span>
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</div>
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</div>
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<div class="explain-item">
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<span class="explain-icon">✏️</span>
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<div class="explain-content">
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<strong>DOM 操作</strong>
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<span>JavaScript 可以增加、删除、修改 DOM 树上的节点。修改节点后，浏览器会重新计算布局并重新绘制页面，这就是"DOM 操作"。</span>
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</div>
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</div>
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</div>
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<div class="info-box">
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<strong>关键概念：</strong>
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<span>DOM 是浏览器在内存中维护的一棵树，它和你写的 HTML 一一对应。JavaScript 无法直接修改 HTML 文件，它修改的是这棵 DOM 树——浏览器再根据 DOM 树的变化更新屏幕上的显示。</span>
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</div>
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</div>
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</template>
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<script setup>
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import { ref } from 'vue'
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const highlightedTag = ref('')
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const htmlLines = [
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{ text: '<html>', indent: 0, tag: 'html' },
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{ text: '<body>', indent: 1, tag: 'body' },
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{ text: '<h1>我的购物车</h1>', indent: 2, tag: 'h1' },
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{ text: '<p>共 3 件商品</p>', indent: 2, tag: 'p' },
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{ text: '<ul>', indent: 2, tag: 'ul' },
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{ text: '<li>耳机</li>', indent: 3, tag: 'li1' },
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{ text: '<li>键盘</li>', indent: 3, tag: 'li2' },
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{ text: '<li>鼠标</li>', indent: 3, tag: 'li3' },
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{ text: '</ul>', indent: 2, tag: 'ul' },
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{ text: '<button>结算</button>', indent: 2, tag: 'btn' },
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{ text: '</body>', indent: 1, tag: 'body' },
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{ text: '</html>', indent: 0, tag: 'html' }
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]
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const treeNodes = [
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{ id: 1, label: 'html', depth: 0, tag: 'html' },
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{ id: 2, label: 'body', depth: 1, tag: 'body' },
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{ id: 3, label: 'h1', depth: 2, tag: 'h1', text: '我的购物车' },
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{ id: 4, label: 'p', depth: 2, tag: 'p', text: '共 3 件商品' },
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{ id: 5, label: 'ul', depth: 2, tag: 'ul' },
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{ id: 6, label: 'li', depth: 3, tag: 'li1', text: '耳机' },
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{ id: 7, label: 'li', depth: 3, tag: 'li2', text: '键盘' },
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{ id: 8, label: 'li', depth: 3, tag: 'li3', text: '鼠标' },
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{ id: 9, label: 'button', depth: 2, tag: 'btn', text: '结算' }
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]
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</script>
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<style scoped>
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.what-is-dom-demo {
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border: 1px solid var(--vp-c-divider);
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border-radius: 6px;
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background-color: var(--vp-c-bg-soft);
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padding: 0.75rem;
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margin: 0.5rem 0;
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}
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.demo-header {
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display: flex;
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flex-wrap: wrap;
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align-items: baseline;
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gap: 0.5rem;
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margin-bottom: 0.75rem;
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}
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.demo-header .title {
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font-size: 1rem;
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font-weight: 600;
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}
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.demo-header .subtitle {
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font-size: 0.85rem;
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color: var(--vp-c-text-2);
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}
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.demo-body {
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display: grid;
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grid-template-columns: 1fr auto 1fr;
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gap: 0.5rem;
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margin-bottom: 0.75rem;
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}
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.html-panel,
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.tree-panel {
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background: var(--vp-c-bg);
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border: 1px solid var(--vp-c-divider);
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border-radius: 6px;
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padding: 0.6rem;
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}
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.panel-title {
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font-size: 0.78rem;
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font-weight: 600;
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color: var(--vp-c-text-2);
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margin-bottom: 0.5rem;
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}
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.code-display {
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font-family: var(--vp-font-family-mono);
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font-size: 0.75rem;
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line-height: 1.6;
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}
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.code-line {
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display: flex;
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align-items: center;
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gap: 0.4rem;
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padding: 0.1rem 0.3rem;
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border-radius: 3px;
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cursor: default;
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transition: background 0.15s;
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}
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.code-line.highlighted {
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background: rgba(59, 130, 246, 0.1);
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}
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.line-num {
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color: var(--vp-c-text-3);
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font-size: 0.65rem;
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min-width: 1rem;
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text-align: right;
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flex-shrink: 0;
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user-select: none;
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}
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.line-code {
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color: var(--vp-c-text-1);
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}
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.arrow-col {
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display: flex;
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flex-direction: column;
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align-items: center;
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justify-content: center;
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gap: 0.3rem;
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padding-top: 1.5rem;
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}
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.arrow-label {
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font-size: 0.68rem;
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color: var(--vp-c-text-2);
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writing-mode: vertical-rl;
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white-space: nowrap;
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}
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.arrow-icon {
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font-size: 1.2rem;
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color: var(--vp-c-brand);
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font-weight: bold;
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}
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.tree-display {
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font-family: var(--vp-font-family-mono);
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font-size: 0.75rem;
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line-height: 1.7;
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}
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.tree-node {
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display: flex;
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align-items: center;
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gap: 0.3rem;
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padding: 0.1rem 0.3rem;
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border-radius: 3px;
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cursor: default;
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transition: background 0.15s;
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}
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.tree-node.highlighted {
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background: rgba(59, 130, 246, 0.1);
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}
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.connector {
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color: var(--vp-c-text-3);
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font-size: 0.7rem;
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flex-shrink: 0;
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}
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.node-tag {
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background: var(--vp-c-bg-alt);
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border: 1px solid var(--vp-c-divider);
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border-radius: 3px;
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padding: 0 0.3rem;
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font-weight: 600;
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font-size: 0.72rem;
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color: var(--vp-c-brand);
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}
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.tree-node.highlighted .node-tag {
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border-color: var(--vp-c-brand);
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}
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.node-text {
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color: var(--vp-c-text-2);
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font-size: 0.7rem;
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}
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.dom-explain {
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display: grid;
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grid-template-columns: repeat(3, 1fr);
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gap: 0.5rem;
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margin-bottom: 0.75rem;
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}
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.explain-item {
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background: var(--vp-c-bg);
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border: 1px solid var(--vp-c-divider);
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border-radius: 6px;
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padding: 0.6rem;
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display: flex;
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gap: 0.4rem;
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}
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.explain-icon {
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font-size: 1rem;
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flex-shrink: 0;
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}
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.explain-content {
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font-size: 0.78rem;
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color: var(--vp-c-text-2);
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line-height: 1.4;
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}
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.explain-content strong {
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display: block;
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color: var(--vp-c-text-1);
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margin-bottom: 0.15rem;
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font-size: 0.8rem;
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}
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.explain-content code {
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background: var(--vp-c-bg-alt);
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padding: 0 0.2rem;
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border-radius: 2px;
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font-size: 0.72rem;
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}
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.info-box {
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background: var(--vp-c-bg-alt);
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padding: 0.75rem;
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border-radius: 6px;
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font-size: 0.85rem;
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color: var(--vp-c-text-2);
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display: flex;
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gap: 0.25rem;
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}
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.info-box strong {
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white-space: nowrap;
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flex-shrink: 0;
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color: var(--vp-c-text-1);
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}
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@media (max-width: 720px) {
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.demo-body {
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grid-template-columns: 1fr;
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}
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.arrow-col {
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flex-direction: row;
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padding-top: 0;
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}
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.arrow-label {
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writing-mode: horizontal-tb;
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}
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.dom-explain {
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grid-template-columns: 1fr;
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}
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}
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</style>
|
