Theming disabled by hard-coded colors

[frie]

There are a couple of "hard-coded" color stylings (background:white;) in the scss sources which do not make use of the color variables, so there currently is no way to change the coloring to a dark theme without touching the sources. At some places background: $white; is coded, which may be overriden by defining $white as black color... See .cui-list class

Originally posted by @frie in https://github.com/vrimar/construct-ui/issues/30#issuecomment-1752600694