Describe the bug
When I want to use the styles attribute to customize the native html tag style, for example: blockquote, but the style that ends up being generated to the page is repeated twice

To Reproduce

1. clone my reproduction project blog production
2. yarn install & yarn start
3. Click the Blog header
4. Route to the named reproduction article
5. Inspect text content is "this is theme-ui style custom style" element

Expected behavior

I don't know why generate duplication css output,that should generate css only once

Screenshots

Additional context
As long as the styles defined from the styles object of theme-ui config have the problem of generating duplicate css