customising side bar colours in webhelp format

I have added some css to customise the colours of the default webhelp presentation.

Where I get stuck is there is a hardcoded style that I cannot override, that I can see is being generated in webhelp/common/main.js:

syncToc() {

   ulNode.setAttribute("style", "display: block; background-color: #D8D8D8 !important;");

}

Why does this style need to be hardcoded here? Couldn't it be covered by the css?

Nat