Dim screen on alert of div

[eminem52]

Following is my css and div, the div when pop up as alert box (happening) i want the rest of the screen around go dim. but my trick is not working at all i am trying to do it only with css. Can we dim the screen around the focused div only with css. Kindly let me know how can i do that. thanks,\[code\].dim { height:100%; width:100%; position:fixed; left:0; top:0; z-index:1 !important; background-color:black; filter: alpha(opacity=75); /* internet explorer */ -khtml-opacity: 0.75; /* khtml, old safari */ -moz-opacity: 0.75; /* mozilla, netscape */ opacity: 0.75; /* fx, safari, opera */}<div class="dim" id="dialog" title="Event"> <p>This is the default dialog which is useful for displaying information. The dialog window can be moved, resized and closed with the 'x' icon.</p></div>\[/code\]