Author: conrad.irwin
Description:
If a username is > 242 bytes (highly unlikely, I know) then appending "/monobook.css" will put the page over the 255 byte limit.
The easiest solution would seem to be to limit user-names to a meagre 235 bytes (58 4-byte characters instead of the current 63 still seems perfectly long enough for something one has to type - and indeed enwiki uses Titleblacklist to reduce this to 40), and skin names to 15 (currently cologneblue is 11).
Version: unspecified
Severity: trivial