corry - Categories Dressing will not work on the Documents sidebox, only the Categories sidebox. If you have installed Categories Dressing, you can get the two-box appearance by creating "category groups" (like #catGroup48 etc.).
Code:
/*example for custom category group styling*/
ul#catGroup48 {
    border: 1px solid #bd6699;
    background: #bbeeff; 
    position: relative;
    left: -1.3em;
    top: 0.2em;
    }
The readme has more information; post back if you still need help.