fix(style): 删除黑暗模式下冗余的样式代码，修复黑暗模式下弹框、demo目录下、按钮样式问题

[zwtvip]

General

✏️ Mark the necessary items without changing the structure of the PR template.

• Pull request template structure not broken

Type

ℹ️ What types of changes does your code introduce?

👉 Put an x in the boxes that apply

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Checklist

ℹ️ Check all checkboxes - this will indicate that you have done everything in accordance with the rules in CONTRIBUTING.

👉 Put an x in the boxes that apply.

• My code follows the style guidelines of this project
• Is the code format correct
• Is the git submission information standard?
• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules