position: fixed; partially renders div when in update panel

Hi All,

I have a div placed in updatepanel. 

When i keep css of my div as below it displays fully ;

<div runat ="server" id ="divNotificationMsg" style="display:none; z-index:10000; position:absolute; left:10%; top:10%; width:80%; padding: 15px 5px;" >

whereas when i keep below the div gets cut off partially from right.

<div runat ="server" id ="divNotificationMsg" style="display:none; background-color:#FFFFFF; z-index:10000; position:fixed; left:10%; top:10%; width:80%; padding: 15px 5px;" >