// javascript to do random numbers
  
function randNum (num) {   

return (1 + (Math.floor(Math.random() * num)));

}
        
var randomBack = 0+randNum(5);
var msg="<style type=\"text/css\"> .contentLeft { background-image: url(images/bg_contentLeft_tape"+randomBack+".jpg) ;} </style>";
document.write(msg);