docs(theme): improve built-in component style

[Wxh16144]

[中文版模板 / Chinese template]

🤔 This is a ...

• New feature
• Bug fix
• Site / documentation update
• Demo update
• Component style update
• TypeScript definition update
• Bundle size optimization
• Performance optimization
• Enhancement feature
• Internationalization
• Refactoring
• Code style optimization
• Test Case
• Branch merge
• Workflow
• Other (about what?)

🔗 Related issue link

💡 Background and solution

📝 Changelog

Language	Changelog
🇺🇸 English	--
🇨🇳 Chinese	改进内置组件样式

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⚠️ Please check all items below before requesting a reviewing. ⚠️

• Doc is updated/provided or not needed
• Demo is updated/provided or not needed
• TypeScript definition is updated/provided or not needed
• Changelog is provided or not needed

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Visual Regression Report for PR #46414

Target branch: master (acbbbfe)

---

Congrats! No visual-regression diff found

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Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (acbbbfe) 100.00% compared to head (0e9e315) 100.00%.

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Additional details and impacted files

@@            Coverage Diff            @@
##            master    #46414   +/-   ##
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  Coverage   100.00%   100.00%           
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  Files          708       708           
  Lines        12120     12120           
  Branches      3217      3217           
=========================================
  Hits         12120     12120           

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[afc163]

样式和官方组件不太一样：https://ant.design/components/alert-cn#components-alert-demo-icon

[Wxh16144]

https://ant.design/components/alert-cn#components-alert-demo-icon

我无脑 copy 了， 晚点我重新搞一下~

[afc163]

ci 挂了