diff --git a/frontend/src/components/common/MarkdownContent.vue b/frontend/src/components/common/MarkdownContent.vue
index 6580f2e..f799288 100644
--- a/frontend/src/components/common/MarkdownContent.vue
+++ b/frontend/src/components/common/MarkdownContent.vue
@@ -17,32 +17,32 @@ watch(() => props.source, async (source) => {
   <div class="markdown-content" v-html="html" />
 </template>
 
-<style scoped>
+<style>
 .markdown-content { white-space: normal; user-select: text; }
-.markdown-content :deep(p), .markdown-content :deep(ul), .markdown-content :deep(ol), .markdown-content :deep(pre), .markdown-content :deep(blockquote) { margin: .65em 0; }
-.markdown-content :deep(h1), .markdown-content :deep(h2), .markdown-content :deep(h3) { margin: 1em 0 .5em; line-height: var(--line-height-tight); }
-.markdown-content :deep(ul) { padding-left: 1.5em; list-style: disc; }
-.markdown-content :deep(ol) { padding-left: 1.5em; list-style: decimal; }
-.markdown-content :deep(li::marker) { color: var(--color-markdown-marker); font-weight: 700; }
-.markdown-content :deep(.shiki) { overflow: auto; margin: .85em 0; padding: 16px; border: 1px solid var(--color-code-border); border-radius: 6px; background: var(--color-code-background) !important; color: var(--color-code-text); font-family: var(--font-ui-mono); font-size: .875em; line-height: 1.45; tab-size: 4; }
-.markdown-content :deep(code) { padding: .1em .3em; border-radius: var(--radius-sm); background: var(--color-background-tertiary); font-family: var(--font-ui-mono); }
-.markdown-content :deep(.shiki code) { display: block; min-width: max-content; padding: 0; background: transparent; font: inherit; }
-.markdown-content :deep(.shiki .line) { display: block; min-height: 1.45em; }
-.markdown-content :deep(blockquote) { padding-left: 1em; border-left: 3px solid var(--color-accent-primary); color: var(--color-text-secondary); }
-.markdown-content :deep(table) { width: 100%; margin: .65em 0; border-collapse: collapse; }
-.markdown-content :deep(th), .markdown-content :deep(td) { padding: .45em .65em; border: 1px solid var(--color-markdown-grid); text-align: left; }
-.markdown-content :deep(th) { background: var(--color-markdown-table-header); font-weight: 700; }
-.markdown-content :deep(img) { max-width: 100%; }
-.markdown-content :deep(hr) { margin: 1em 0; border: 0; border-top: 1px solid var(--color-border-default); }
-:global([data-code-theme='github-light']) .markdown-content :deep(.shiki),
-:global([data-code-theme='github-light']) .markdown-content :deep(.shiki span) {
+.markdown-content p, .markdown-content ul, .markdown-content ol, .markdown-content pre, .markdown-content blockquote { margin: .65em 0; }
+.markdown-content h1, .markdown-content h2, .markdown-content h3 { margin: 1em 0 .5em; line-height: var(--line-height-tight); }
+.markdown-content ul { padding-left: 1.5em; list-style: disc; }
+.markdown-content ol { padding-left: 1.5em; list-style: decimal; }
+.markdown-content li::marker { color: var(--color-markdown-marker); font-weight: 700; }
+.markdown-content .shiki { overflow: auto; margin: .85em 0; padding: 16px; border: 1px solid var(--color-code-border); border-radius: 6px; background: var(--color-code-background) !important; color: var(--color-code-text); font-family: var(--font-ui-mono); font-size: .875em; line-height: 1.45; tab-size: 4; }
+.markdown-content code { padding: .1em .3em; border-radius: var(--radius-sm); background: var(--color-background-tertiary); font-family: var(--font-ui-mono); }
+.markdown-content .shiki code { display: block; min-width: max-content; padding: 0; background: transparent; font: inherit; }
+.markdown-content .shiki .line { display: block; min-height: 1.45em; }
+.markdown-content blockquote { padding-left: 1em; border-left: 3px solid var(--color-accent-primary); color: var(--color-text-secondary); }
+.markdown-content table { width: 100%; margin: .65em 0; border-collapse: collapse; }
+.markdown-content th, .markdown-content td { padding: .45em .65em; border: 1px solid var(--color-markdown-grid); text-align: left; }
+.markdown-content th { background: var(--color-markdown-table-header); font-weight: 700; }
+.markdown-content img { max-width: 100%; }
+.markdown-content hr { margin: 1em 0; border: 0; border-top: 1px solid var(--color-border-default); }
+[data-code-theme='github-light'] .markdown-content .shiki,
+[data-code-theme='github-light'] .markdown-content .shiki span {
   color: var(--shiki-light) !important;
   font-style: var(--shiki-light-font-style) !important;
   font-weight: var(--shiki-light-font-weight) !important;
   text-decoration: var(--shiki-light-text-decoration) !important;
 }
-:global([data-code-theme='github-dark']) .markdown-content :deep(.shiki),
-:global([data-code-theme='github-dark']) .markdown-content :deep(.shiki span) {
+[data-code-theme='github-dark'] .markdown-content .shiki,
+[data-code-theme='github-dark'] .markdown-content .shiki span {
   color: var(--shiki-dark) !important;
   font-style: var(--shiki-dark-font-style) !important;
   font-weight: var(--shiki-dark-font-weight) !important;
diff --git a/frontend/src/features/editor/VisualMarkdownEditor.vue b/frontend/src/features/editor/VisualMarkdownEditor.vue
index 6a37edc..ca28e6d 100644
--- a/frontend/src/features/editor/VisualMarkdownEditor.vue
+++ b/frontend/src/features/editor/VisualMarkdownEditor.vue
@@ -288,6 +288,6 @@ defineExpose({ getEditor: () => crepe?.editor })
 .milkdown-host :deep(.milkdown-list-item-block li .label-wrapper) { color: var(--color-markdown-marker); font-weight: 700; }
 .milkdown-host :deep(.milkdown-list-item-block li .label-wrapper svg) { fill: var(--color-markdown-marker); }
 .milkdown-host :deep(code) { font-family: var(--font-editor-mono); }
-:global([data-theme='dark']) .milkdown-host :deep(.milkdown) { color-scheme: dark; }
+:global([data-theme='dark'] .milkdown-host .milkdown) { color-scheme: dark; }
 @media (max-width: 680px) { .toolbar-select select { min-width: 46px; width: 46px; } }
 </style>
diff --git a/frontend/src/features/themes/ThemesView.vue b/frontend/src/features/themes/ThemesView.vue
index 1a93a5d..33ebc69 100644
--- a/frontend/src/features/themes/ThemesView.vue
+++ b/frontend/src/features/themes/ThemesView.vue
@@ -1,6 +1,15 @@
 <script setup lang="ts">
+import { computed } from 'vue'
+import MarkdownContent from '@/components/common/MarkdownContent.vue'
 import { useThemeStore } from '@/stores/theme'
+
 const themeStore = useThemeStore()
+const shikiPreview = `\`\`\`typescript
+const notes = await search('本地优先')
+\`\`\``
+const codeThemeLabel = computed(() => themeStore.resolvedCodeBlockTheme === 'github-dark'
+  ? 'Shiki · GitHub Dark'
+  : 'Shiki · GitHub Light')
 </script>
 
 <template>
@@ -13,7 +22,20 @@ const themeStore = useThemeStore()
         <p class="subtle">v{{ theme.version }} · {{ theme.builtin ? '内置主题' : theme.author }}</p>
       </button>
     </div>
-    <div class="panel preference-panel"><h2 class="panel-title">编辑器外观</h2><div class="form-grid"><div class="field"><label>字号：{{ themeStore.fontEditorSize }}px</label><input v-model.number="themeStore.fontEditorSize" type="range" min="12" max="24" /></div><div class="field"><label>行高：{{ themeStore.lineHeight }}</label><input v-model.number="themeStore.lineHeight" type="range" min="1.2" max="2.2" step="0.1" /></div><div class="field"><label>字体</label><select v-model="themeStore.fontEditorFamily" class="select"><option value="system-ui">系统字体</option><option value="serif">衬线字体</option><option value="var(--font-ui-mono)">等宽字体</option></select></div><div class="field"><label>代码块样式</label><select v-model="themeStore.codeBlockTheme" class="select"><option value="auto">跟随主题</option><option value="github-light">GitHub Light</option><option value="github-dark">GitHub Dark</option></select><small>Markdown 渲染使用对应的 Shiki GitHub 主题</small></div></div><div class="editor-preview" :style="{ fontSize: `${themeStore.fontEditorSize}px`, lineHeight: themeStore.lineHeight, fontFamily: themeStore.fontEditorFamily }"><h3>主题预览</h3><p>知识的价值不只在于保存，更在于被重新发现和使用。</p><pre class="code-preview"><code><span class="code-keyword">const</span> <span class="code-variable">notes</span> = <span class="code-keyword">await</span> <span class="code-function">search</span>(<span class="code-string">'本地优先'</span>)</code></pre></div></div>
+    <div class="panel preference-panel">
+      <h2 class="panel-title">编辑器外观</h2>
+      <div class="form-grid">
+        <div class="field"><label>字号：{{ themeStore.fontEditorSize }}px</label><input v-model.number="themeStore.fontEditorSize" type="range" min="12" max="24" /></div>
+        <div class="field"><label>行高：{{ themeStore.lineHeight }}</label><input v-model.number="themeStore.lineHeight" type="range" min="1.2" max="2.2" step="0.1" /></div>
+        <div class="field"><label>字体</label><select v-model="themeStore.fontEditorFamily" class="select"><option value="system-ui">系统字体</option><option value="serif">衬线字体</option><option value="var(--font-ui-mono)">等宽字体</option></select></div>
+        <div class="field"><label>代码块样式</label><select v-model="themeStore.codeBlockTheme" class="select"><option value="auto">跟随主题</option><option value="github-light">GitHub Light</option><option value="github-dark">GitHub Dark</option></select><small>Markdown 渲染使用对应的 Shiki GitHub 主题</small></div>
+      </div>
+      <div class="editor-preview" :style="{ fontSize: `${themeStore.fontEditorSize}px`, lineHeight: themeStore.lineHeight, fontFamily: themeStore.fontEditorFamily }">
+        <div class="preview-heading"><h3>主题预览</h3><span class="badge info">{{ codeThemeLabel }}</span></div>
+        <p>知识的价值不只在于保存，更在于被重新发现和使用。</p>
+        <MarkdownContent class="code-theme-preview" :source="shikiPreview" />
+      </div>
+    </div>
   </section>
 </template>
 
@@ -29,14 +51,7 @@ const themeStore = useThemeStore()
 .preference-panel { display: grid; gap: var(--space-xl); }
 .editor-preview { padding: var(--space-xl); border: 1px solid var(--color-border-default); border-radius: var(--radius-md); background: var(--color-background-secondary); }
 .editor-preview p { margin: var(--space-sm) 0; }
+.preview-heading { display: flex; align-items: center; justify-content: space-between; gap: var(--space-md); }
 .field small { color: var(--color-text-tertiary); }
-.code-preview { overflow: auto; margin-top: var(--space-md); padding: 16px; border: 1px solid var(--color-code-border); border-radius: 6px; background: var(--color-code-background); color: var(--color-code-text); font: 13px/1.45 var(--font-ui-mono); }
-:global([data-code-theme='github-light']) .code-keyword { color: #cf222e; }
-:global([data-code-theme='github-light']) .code-variable { color: #24292f; }
-:global([data-code-theme='github-light']) .code-function { color: #8250df; }
-:global([data-code-theme='github-light']) .code-string { color: #0a3069; }
-:global([data-code-theme='github-dark']) .code-keyword { color: #ff7b72; }
-:global([data-code-theme='github-dark']) .code-variable { color: #c9d1d9; }
-:global([data-code-theme='github-dark']) .code-function { color: #d2a8ff; }
-:global([data-code-theme='github-dark']) .code-string { color: #a5d6ff; }
+.code-theme-preview { margin-top: var(--space-md); }
 </style>
diff --git a/frontend/src/styles/motion.spec.ts b/frontend/src/styles/motion.spec.ts
index 59f8e82..49cad55 100644
--- a/frontend/src/styles/motion.spec.ts
+++ b/frontend/src/styles/motion.spec.ts
@@ -10,6 +10,7 @@ const globalStyles = [
 
 const markdownStyles = [
   new URL('../features/editor/VisualMarkdownEditor.vue', import.meta.url),
+  new URL('../features/themes/ThemesView.vue', import.meta.url),
   new URL('../components/common/MarkdownContent.vue', import.meta.url),
 ].map((path) => readFileSync(path, 'utf8')).join('\n')
 
@@ -36,4 +37,8 @@ describe('轻量动效基线', () => {
     expect(markdownStyles).toContain('var(--color-markdown-grid)')
     expect(markdownStyles).toContain('var(--color-markdown-marker)')
   })
+
+  it('不混用可能丢失后代选择器的 scoped global 写法', () => {
+    expect(markdownStyles).not.toMatch(/:global\([^\n]+\)\s+\./)
+  })
 })