I can't seem to find what to change to hide the sidebox heading labels....(Search by category, search by manufacturer, shopping cart, login, featured items, etc.... )

I have separate images I would like to use for each of the different sidebox headings and I found this in the stylesheet which I'm assuming is what I should be looking at....

h3.leftBoxHeading, h3.leftBoxHeading a, h3.leftBoxHeading label, h3.rightBoxHeading, h3.rightBoxHeading a, h3.rightBoxHeading label {
font-size: 10px;
color: #ffffff;
}
BUT i can't figure out how to just hide the FONT. It hides the background color and everything else.............