Color & Transparency settings for Slicer Dropdown background list

Currently we are not able to directly change the dropdown color of a slicer dropdown list. It is possible only by importing a custom json theme file, but we can only make it full transparent, we can't make it 50% transparent or 20% transparent. . It would be great if we have the flexibility to do that in Format options. Change the color of the dropdown list and also change the Transparency settings.

Thank You,

Pratik