In Editor var(--color) preview - StyleSheets CSS Editor import
Now Oxygen Builder supports using CSS variables, but it does not show color preview.
Import all stylesheets inside Editor.
CSS collison with Editor, breaking few things. If collision happens you can use Quick Fix to remove it from Editor.
Potential better solution in future:
Marking stylesheet with color variables with some special comment */##COLOR##/* which could make parsing easy. So if stylesheet is starting with that comment it will be pulled inside Editor for eg.