To change the color of the checkout bar on the cart page modify the following styles in the module.css
/* Cart styles */
td.CartHeader
{
background: #006699;
padding: 3px 3px 3px 3px;
}
.CartHeadText
{
font-family:Verdana, Arial, Helvetica, sans-serif;
font-size: 13px;
color:#FFFFFF;
font-weight: bold;
}