window.onload = function() {
    resizeTextArea();
}
window.onresize=function(){
    resizeTextArea();
}


function resizeTextArea(){
    var ta=document.getElementById("background");
    var myw=0.9*(getBrowserWidth());
    var myh=1.0*(getBrowserHeight());

    var mycss="width:"+myw+"px;height:"+myh+"px;background:url(http://www.funy.jp/img/background.gif) repeat-y;";
    ta.style.cssText=mycss;
}
function getBrowserWidth() {  
    if ( window.innerWidth ) {
        return window.innerWidth; 
    } 
    else if ( document.documentElement && document.documentElement.clientWidth != 0 ) {
        return document.documentElement.clientWidth; 
    }
    else if ( document.body ) {
        return document.body.clientWidth;
    }
    return 0;  
}  
function getBrowserHeight() {  
    if ( window.innerHeight ) {
        return window.innerHeight; 
    } 
    else if ( document.documentElement && document.documentElement.clientHeight != 0 ) {
        return document.documentElement.clientHeight; 
    }
    else if ( document.body ) {
        return document.body.clientHeight;
    }
    return 0;  
}