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.
If I were using a preprocessor, I'd just use the in-built variables of that preprocessor I guess.