th.header {
    background-image: url(../images/bg.gif);
    cursor: pointer;
    font-weight: bold; 
    background-repeat: no-repeat;
    background-position: center right;
    padding-left: 20px;
    margin-left: -1px;
}

th.headerSortDown {
    background-image: url(../images/desc.gif);
}

th.headerSortUp {
    background-image: url(../images/asc.gif);
}