<style lang="stylus">
  p
    color black
</style>

<style lang="stylus" theme="light">
  p
    color white
</style>

I'd like to be able to create component themes given an attribute name. Idealistically no theme attribute would roll up into the default css file and style blocks with the theme attribute would roll up in a css file of that name.

I'm willing to do the leg work on this and put in a PR if it sounds reasonable.