Forgot to update the 404 page/associated JS last week

Fixed the issue involving opening links in new tabs. Had to tweak some JS.

There's a weird issue I'm getting on my end where hashes aren't being entirely copied over when opening pages in new tabs or opening them from Neocities in this update post. No clue why it's doing that, but it works fine on my local test server.

Found and fixed some issues with the new stuff.