body { overflow:auto; background-color:#fff; } #Content { position:absolute; left:50%; top:50%; width:300px; height:320px; margin-left:-150px; /* width/2 */ margin-top:-160px; /* height/2 */ border:1px dashed #333; background-color:#eee; padding:10px; } /* The right value for Mozilla */ body>#content { margin-left:-160px; margin-top:-170px; }