User blog comment:Kirkburn/Syntax highlighting - helping you read and write code/@comment-452-20150410203600/@comment-5288784-20150410221246

Oh, my bad, so it is influenced by that highlighting code. The way this thing is handled with negative margins are a bit unusual, no wonder the regular browser search bar doesn't know what it should do. Still, that's some tips how you can bypass the bug until it's fixed. Also, scrolling to the very right should unlock you the proper scroll to te left. Alternatively, you can use monobook in the meantime.