.mega_logobox {
    float: left;
    margin-left: 2px;
    margin-top: 33px;
    padding-bottom: 30px;
    width: 300px; /* you an change width value here */
}

and

a.mega_logo {
    background: url("../images/brown/logo.png") no-repeat scroll 0 0 transparent;
    border-right: 1px solid #5A5A5A;
    display: block;
    height: 36px;
    margin-right: 10px;
    padding-right: 15px;
    width: 137px; /* you an change width value here */
}