Bootswatch - Don't use variables for add content modal

Whereas it's a really cool idea to allow the look and feel of the "add content" modal to change according to the active theme, there's issues with certain themes, particularly dark ones. Please refer to the attached screenshots for details. Notice the awkward text-shadows and also the poor contrast for the group vertical tabs (this is on "Slate", some dark themes are not legible at all).

Due to the nature of Bootswatch and customizing Bootstrap themes using variables, it's almost impossible to generate generic styles that will make the modal always be legible, so I propose that maybe there might a light and a dark version of the modal and that it's styling be controlled by separate variables (and maybe be customizable per subtheme using a boolean var or something) so that it'll look good independently of the rest of the theme's color scheme.

Thoughts?