CSS or card-colors, background etc build-in home assistant without cardmodder

I find it rather difficult using cardmodder (plus the extra modder because of horzontal-stacs) or HACS and themes to change te looks of the Lovelace Frontend.

Would be nice if you can just add a color-code/transparancy/tekst-color within each card without external work-arounds, wich are too difficult for the average user.

Using the codes like found here: https://cssgenerator.org/filter-css-generator.html