how to set width height of modal window

how to set width height of modal window

Hi,
 
I have a modal window and need to set witdth & height of it. Here is my code for modal window.
 
Setting attribute of width:200px height:300px doesn't work. How would I set it? My browser is IE 7.
 
Many thanks
 
 
  1. <script type="text/javascript">
  2.  $( function()
     {
        $('#ModalForm1').dialog(
        {
       
       modal : true ,
       autoOpen : false ,
       buttons  : {
           Cancel  : function() {
              closeModalAndReset();
             } ,
           Update : function() {
              closeModalAndUpdate();
              
             }
          }














  3.     });
     });