Portfolio Categories Navigation – Colours

Hi,
the categories “menu” on my portfolio page show up well, but I would like it to have a mouse-over effect as in the Demo page (where the buttons have a green background on mouse over, and the font turns to white). On my page, the category menu doesn’t have a mouse over effect and no background color. Tried to change this in the color settings, but couldn’t find it.
Any help is appreciated.