#mygallery1{
text-align: center;
box-shadow: 10px 10px 10px #aaa;
border-radius: 6px;
position: absolute; /*leave this value alone*/
border: 1px solid black;
/*overflow: hidden; leave this value alone*/
width: 640px; 
height: 480px; 
z-index:199;
margin-left: 21%;
}