Style sheet files in this folder are named to match the example document that includes them. 

That is, the example scrollbar.html uses a style sheet names scrollbar.css,
scrollbar_h.html uses scrollbar_h.css, ...

CSS files are included in the example documents using code in the head of the document (for accessibility); for example: 

// if code supported, link in the style sheet (optional) and call the init function onload
if ( dw_scrollObj.isSupported() ) {
    dw_Util.writeStyleSheet('css/scrollbar.css');
    dw_Event.add( window, 'load', init_dw_Scroll);
}


Using xml and need to avoid document.write? Another function is available: 
dw_Util.addLinkCSS('css/scrollbar.css')

Code comments include helpful information.

More information is available in the online documentation at:
http://www.dyn-web.com/code/scroll/documentation.php