if (typeof window_width == 'undefined' || typeof window_height == 'undefined') {  
var window_width;  
var window_height;  
if( typeof( window.innerWidth ) == 'number' ) {  
window_width = window.innerWidth;  
window_height = window.innerHeight;  
} else if( document.documentElement &&  
( document.documentElement.clientWidth || document.documentElement.clientHeight ) ) {  
window_width = document.documentElement.clientWidth;  
window_height = document.documentElement.clientHeight;  
} else if( document.body && ( document.body.clientWidth || document.body.clientHeight ) ) {  
window_width = document.body.clientWidth;  
window_height = document.body.clientHeight;}}