DatePicker 选中的日期背景白色bug

[sxbjxyy]

Is there an existing issue for this?

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Describe the bug

DatePicker 选中的日期背景白色bug，官网也是如此

Expected Behavior

DatePicker 选中的日期背景与未选中不同，给加个背景色即可

Steps To Reproduce

No response

Exceptions (if any)

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.NET Version

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Anything else?

No response

[bb-auto]

@sxbjxyy Thank you for filing this issue. In order for us to investigate this issue, please provide a minimalistic repro project that illustrates the problem.