catagories side box main page

hi hopefully this will be my last post asking a question my site is almost finished. thanks to totally zenned.
in the catagories box on main page i want to change background colour font and make font bold.

When i had the original zen template i sussed out how to do it but i cannot work it out on this templates css style sheet and have searched forum and cant find answer to my problem

I am running zen 1.3.9h with digital shop template.

site address http://www.thearmysurplusstore.co.uk

have installed web developer into mozilla to avoid keeping posting but its not working consistently in tool bar.

dont mean to be a nightmare

thanks for help

start here
in your stylesheet change this:

.sideBoxContent {

background-color: #fffff;
width:160px;
border-bottom:none;

thanks how can i make the font bold?

#categories a {font-weight: bold;}

thanks for all your help job done