My b2evolution Version: 4

Can anyone tell me an easy way to round the corners of items in the top menu bar (ex: where Home, About this System, etc. are here: http://skins.b2evo.net/2/index.php?tempskin=hotairballoons). It seems like whatever is creating the rounded corners on the black bars on the top and bottom could be used to do the same with the menu items, no? Also, is there a way to change the color of the background on the menu items easily?