Matt Gemmell released a script to help author's unobtrusively mark what they felt to be their main points. Not one person said, "can't this be done in pure HTML & CSS?", yet I slapped together a solution anyway.

I've embedded an example below, or if you're into Codepen (like the cool kids), then head over there and do me one better.

Update (2013-05-17): I corrected a spelling error. Mr. Gemmell’s features two m’s which I failed to notice earlier.