What browser/OS etc.?
FWIW here, on Firefox/Debian/x86 I get the same - difference between items up to 'Resources' and those from 'General Information' and on. The former appear as dark blue when highlighted, while the latter pop to white. Additionally, the first set have slightly darker lines between each item (the latter has consistent blue background) and take longer to appear and disappear - the latter appear almost instantly and fade quickly.
Not a big issue though. The earlier menus take a little too long to appear on this here cranky old netbook, but I don't use them often so am not really bothered.