rounded category strips?

[5th-Level]

I want rounded category strips and i tried Dans way and it doestnt work it gives me alot of errors so i did it in CSS and i dont know how to put it in the template

Does anyone have a good tutorial for rounded category strips?

BTW:

My CSS in "Additional CSS Definitions"

.header_l{
background: url($stylevar[imgdir_misc]/top_left.png) no-repeat top left; height: 34px; }

.header_r{
background: url($stylevar[imgdir_misc]/top_lright.png) no-repeat top right; height: 34px; }

.header_bg{
 background: url($stylevar[imgdir_misc]/top_x.png) repeat-x top left; height: 34px; }
}

Where would i place this in the forum_1_nopost template?