You can try this:
.nabble tr.category-row,
.nabble tr.header-row {
background-image: url('http://www.onlinebizteam.com/images/onlinebizteam/onlinebizteam_headbg.gif');
background-repeat: repeat-x;
}
.nabble tr.category-row,
.nabble tr.category-row a,
.nabble tr.category-row td,
.nabble tr.header-row,
.nabble tr.header-row a,
.nabble tr.header-row td
{
color: #FFFFFF;
}
.nabble tr.main-row {
background: url('/images/homepage/gray.png') repeat-x;
}