Edit style.css, add following at the end

pre {
    background: url("http://blog.hostonnet.com/files_hon/wp_pre_bg.gif") repeat scroll left top #FFFFFF;
    border: 1px solid #999999;
    color: #000000;
    display: block;
    font-family: "Courier New",Courier,monospace;
    font-size: 13px;
    line-height: 18px;
    margin: 10px 0 20px;
    overflow-x: scroll;
    overflow-y: auto;
    padding: 18px 10px 17px;
    position: relative;
    z-index: 50;
}