I've done a bit of custom CSS on my anime list; most notably on the premiere date columns. Here is what each type of formatting means:
1990s or earlier
Current season (I have to manually update this so it tends to be outdated)
I have a couple other tweaks in place, but the rest of them shouldn't need explanation. Feel free to reuse any of my CSS on your own list. You can find it by viewing the page source (google how to do this for your browser if you don't know) and searching the page for "custom-css". I've added comments explaining what each bit does so you can pick which bits you want to copy.