Adjusting Category Sidebar CSS

[ZuluRose]

Hi,

I want to change my Categories header to a different font.
But ONLY my categories. I would like for my other sidebar items to retain the same formatting.

Here is my site for reference.
http://www.zulurose.com
(I renamed Categies to Collection)

Attached is a screen shot of how I would like the layout to be.

I already have a CSS style called: .leftBoxContainerItalic
But were do I assign it?

[clydejones]

Add this to your stylesheet.css

h3#categoriesHeading {font-style: italic;}

[ZuluRose]

Thanks Clyde,

That did the trick.