Providing auto height and width to dialog in jquery UI modal dialog box

I am try开发者_如何学Going to put auto height and width to modal dialog box (provided by jQuery UI). But some how the position of my dialog is getting disturbed. It is not coming in center. Every time I click on the link to open the dialog box, the dialog opens at different position. Could anybody please suggest how to resolve this issue...

---

u can main

div 

{
 margin:0 auto;
}
or
{
 margin:auto auto;
}

==========

Othervise u can set a left and top javascript dailog box position set...

thanks suresh