There looks to be a decided amount of instability in how implementing this might work. If one handcodes the CSS and never touches it any other way, sure you might be able to make the fiddliness work. But if anything ever re-organizes your CSS file, or you utilize !important one too many times, or forget whether your 'recipe' tag or your 'needs commentary' tag has primacy... it could all come sideways.

And while that's bad enough to do to your own personal view of a post, changing everybody's view makes it catastrophically unstable.