fix(code-block): apply shiki theme bg to wrapping td

The Shiki theme background only landed on the `<pre>`, leaving the td's
mso-padding-alt-4 area to show through as white in Outlook — visible as a
white frame around dark themes.

Author: cossssmin

src/components/CodeBlock.vue

@@ -61,7 +61,7 @@ export default {
     const baseStyles = `background-color:${bg};padding:16px;overflow:auto;white-space:pre;word-wrap:normal;word-break:normal;word-spacing:normal`
     const styles = [baseStyles, attrs.style].filter(Boolean).join(';')
 
-    const html = `<table class="w-full"><tr><td class="${props.tdClass}"><pre class="${classes}" style="${styles}"><code>${codeContent}</code></pre></td></tr></table>`
+    const html = `<table class="w-full"><tr><td class="${props.tdClass}" style="background-color:${bg}"><pre class="${classes}" style="${styles}"><code>${codeContent}</code></pre></td></tr></table>`
 
     return () => createStaticVNode(html, 1)
   }

src/tests/components/CodeBlock.test.ts

@@ -74,13 +74,27 @@ describe('CodeBlock', () => {
     it('uses default td-class', async () => {
       const html = await render({ code: '<div>test</div>' })
 
-      expect(html).toContain('<td class="max-w-0 mso-padding-alt-4">')
+      expect(html).toContain('<td class="max-w-0 mso-padding-alt-4"')
     })
 
     it('accepts custom td-class', async () => {
       const html = await render({ code: '<div>test</div>', 'td-class': 'custom-class' })
 
-      expect(html).toContain('<td class="custom-class">')
+      expect(html).toContain('<td class="custom-class"')
+    })
+
+    it('sets the shiki theme background on the wrapping td', async () => {
+      const html = await render({ code: '<div>test</div>' })
+
+      // github-light bg is #fff — must appear on the td so Outlook's td
+      // padding doesn't show through as white on a dark theme.
+      expect(html).toMatch(/<td[^>]*style="background-color:#fff"/)
+    })
+
+    it('uses the dark theme bg on the wrapping td', async () => {
+      const html = await render({ code: '<div>test</div>', theme: 'github-dark' })
+
+      expect(html).toMatch(/<td[^>]*style="background-color:#24292e"/)
     })
   })