Prosilver's select fields under dark desktop themes

Hello.

This isn't specific to any PHP version or database system since it is generalized in all prosilver-based phpBB3 forums.

I explain : my PC is running under Ubuntu (Linux) and lately, I changed my desktop theme for a dark one.
But I noticed that while most textboxes and textareas have both their font color and background color set in their CSS, it isn't the case for drop-down menus who haven't their font color set and so, the text is almost illegible. I attach a screenshot, to show you the issue.

Thanks in advance.

Ishimaru