Options:
- use only variables, and put `body { background: #eee; color: #333; }` so this is the 'fallback'
- prepend a fallback style: `color: red; color: var(main-color);`
- use a css preprocessor to mangle all the things -- somehow.
Prepending the fallback style was the option I was considering, but it does really defeat the whole purpose of the idea. You'd end up with the same styles that you would have without variables, plus all the duplicate rules using variables, all for no gain.
If I were using a preprocessor, I'd just use the in-built variables of that preprocessor I guess.
