I’m trying to make all text white (and remove highlights , not sure how to do that… maybe highlight: none ?? Couldn’t find anything about this in the manual)
font-family: arial;
font-size: 20px;
text-align: center;
color: white !important;
background-color: ;
}```
!important sadly only overwrites other formats, but not the color: html in the notes themselves (inline I think it is called)

This text is heavily preformatted. Perhaps instead of overriding the inline styles it’s better to just use Ctrl+Shift+V to paste the text without formatting or use Anki’s “Remove Formatting” feature on the selected text (rubber icon, Ctrl+R).
There is no built-in feature to remove formatting in bulk, but there may be add-ons that provide such a feature, or you may be able to do it with Find&Replace.