设置theme: "dark"后，不需要背景颜色，需要如何设置呢 #4031

• I have searched the issues of this repository and believe that this is not a duplicate.

What problem does this feature solve?

我使用了下面的方法，但是这样会使得dark主题失效

update({
    theme: {
      styleSheet: {
        backgroundColor: "transparent",
      },
    },
})

What does the proposed API look like?

希望设置dark主题后，同时在该主题的基础上做些额外的设置，比如将背景色transparent

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