Why this would be helpful

Sometimes I want to make a studio thumbnail look better by adding a white background using CSS

My suggestion

Add an option to toggle the studio thumbnail background to white in the "Website dark mode and customizable colors" addon.

Possible alternatives

I... don't know.

Additional context

Before adding the white background:

After adding the white background:

Note: The image class of the studio thumbnail is the studio-image class
<img class="studio-image" src="https://cdn2.scratch.mit.edu/get_image/gallery/337843_170x100.png">
and the thumbnail-image class
<a class="thumbnail-image" href="/studios/337843/"><img alt="" src="https://cdn2.scratch.mit.edu/get_image/gallery/337843_170x100.png"></a>

The studio link in the screenshot:
https://scratch.mit.edu/studios/337843/