Dinesh

use left:0; right:0; margin:auto;

Hi All,
A best simple way to do this
There is no need of wrapper class
for horizontal u can use
.popup{
position:fixed;
width:200px;
height:300px;
left:0;
right:0;
margin:auto;
}
best way

for vertically u need two more css above this in first use display table, in child use display:table-cell; vertical-align:middle;
then use your design div