You can adjust the colors for the individual items in the menu using inline styling. You can add in a style like this to the <a> tag in the menu:
<ul class="level-0" id="cssmw">
<li><a style="background-color:#009933" href="#">Item 1</a></li>
<li><a style="background-color:#009933" href="#">Item 2</a></li>
<li><a style="background-color:#0033CC" href="#">Item 3</a></li>
<li><a style="background-color:#0033CC" href="#">Item 4</a></li>
<li><a style="background-color:#CC3333" href="#">Item 5</a></li>
<li><a style="background-color:#CC3333" href="#">Item 6</a></li>
</ul>
You just add the style inside of the anchor tag.