Add this code to a content editor web part.
<div id="stsclass" name="stsclass"></div>
<script type="text/javascript">
function ClassInfo()
{
if (window.event.srcElement.className != null)
{
stsclass.innerText = window.event.srcElement.className;
}
else
{
stsclass.innerText = "";
}
}
window.document.body.onmouseover = ClassInfo;
</script>
Then hover over those areas. That should give you the class you need to work with. You can then over ride that class on your master page.
Hope that helps,
SharePointNinja