Remove the follow properties:
* clear (wasn't used)
* list-style-* (wasn't used)
* outline (only used a few times; can be achieved with borders or
box-shadow).
* mask (not well-supported in browsers; only used a few times for
effects that could be achieved in other ways).
* text-decoration-* (use the shorthand property)
* text-transform (can be achieved in other ways)
Eliminate the Danbooru.config.hostnames option. It was only used for
rewriting links in notes. Just using the main hostname is good enough,
there aren't any notes still using any of Danbooru's alternate domain
names.
