I’ve implemented that two ways: having JavaScript pop the alternative attribute off for all but the desired style sheet or simply using a top-level class to modify the relatively few things we were customizing. Back in the day, I used SCSS but CSS Variables have matured to the point where you can do an awful lot that way, too.
https://developer.mozilla.org/en-US/docs/Web/CSS/Alternative...
I’ve implemented that two ways: having JavaScript pop the alternative attribute off for all but the desired style sheet or simply using a top-level class to modify the relatively few things we were customizing. Back in the day, I used SCSS but CSS Variables have matured to the point where you can do an awful lot that way, too.