Exclude certain fields from fixtures?

Is there a way to exclude certain fields from fixtures?

Use case: when exporting a Website Theme as a fixture, things like the the generated CSS and the path to the CSS file are exported as well. However, those are auto-generated. The CSS will be generated anyways and the CSS file will not exist at this path on a different machine. The result is that the website loses it’s style after running bench migrate.

@netchampfaris