CSS: set font weight depending on fallback font

Question

I am trying to set the font-weight for an element based on the font that gets chosen. For example, I may be trying to do something like this:

h1 {
    font-f         


        

Answer 1

I'm 99.99999% sure this can't be done without some serious JavaScript magic, and even with JavaScript it's damn difficult to find out which font was used in the end.

Related: get computed font-family in JavaScript asked by yours truly