img {
   position: absolute;
   top: 50%;
   left: 50%;
   width: 300px;
   height: 43px;
   margin-top: -21px; /* Half the height */
   margin-left: -150px; /* Half the width */
}

html, body, #wrapper {
   height:100%;
   width: 100%;
   margin: 0;
   padding: 0;
   border: 0;
}
#wrapper td {
   vertical-align: middle;
   text-align: center;
}