Ah, yes, I see--locally customised CSS is something most people will both never do and be completely bemused by, but every journal theme out there these days uses large amount of CSS in it.

I used to do this sort of thing when I was blogging semi-seriously, but had to hand code the 'class=news' and 'class=LOL' code into each post, this would both be a lot easier, be less likely for me to forget and allow me to go back and amend all my old entries easily, which would be nice.