body { margin: 0 auto; margin-top:0px; width: 600px; background-color:#cccccc; background-repeat:no-repeat;
   background-attachment:fixed; background-position:center center}

#baustelle {
            
            margin-left: auto;
			margin-right: auto;
			margin-top: 100px;
			width:600px;
		    height: 400px;
      
            }