Tested in Firefox

Change log:

v6
- fix broken catalog

v5
- post/file info colors

v4
- fixed main 4chan X menu appearing out of screen
- better default sizing of QR
- changed some colors

v3
- New post border colors: cyan for target post, orange for filter-highlighted
- Add empty area at the top of the page and force QR to occupy it
- Fix 4chan party hat

v2
- longer delay before post/file info disappears
- nicer animations
- posts made by you are dimmed, but appear in full color on mouse-over
- add some padding at the bottom of the thread for quick reply box
- violet border for target post (might look ugly with some themes, but works well with tomorrow)
- (bug fix) post menu doesn't immediately hide when you move your mouse out of it

v1 (initial)
- use flexbox to position the posts
- hide post/file info by default, make it appear on hover
- hide some useless elements like ads