[jQuery] Superfish - vs. 1.4.8 - cannot force background color to span across FULL PAGE

[jQuery] Superfish - vs. 1.4.8 - cannot force background color to span across FULL PAGE


I desperately (always need to) span any menu across the full page. I'm
shocked there are no examples of this. Anyway, it doesn't work. See
example code below. I need to define a css class so that the menu
spans the FULL width of the page.
Any workarounds or do I scrap jQuery??
css:
#menuback {
    background-color: #BDD2FF;
    padding: 0px; margin-left:0px; margin-right: 0px; width:100%;
}
html code:
<div id="menuback">
        <ul class="sf-menu">
            <li class="current">
                <a href="#a">menu item &#8595;</a>
                <ul>
                    <li>
                        <a href="#aa">menu item that is quite long</a>
                    </li>
                </ul>
            </li>
        </ul>
</div>