if (((navigator.userAgent).indexOf("Mac_PowerPC")!=-1)&&((navigator.userAgent).indexOf("MSIE")!=-1)){
document.write('<link rel="stylesheet" type="text/css" href="css/mac_IE.css">');
} else 

if(((navigator.userAgent).indexOf("Windows")!=-1)&&((navigator.userAgent).indexOf("MSIE")!=-1)){
document.write('<link rel="stylesheet" type="text/css" href="css/pc.css">');
}else 

if(((navigator.userAgent).indexOf("Windows")!=-1)&&((navigator.userAgent).indexOf("Opera")!=-1)){
document.write('<link rel="stylesheet" type="text/css" href="css/pc_opera.css">');
}else 

if(((navigator.userAgent).indexOf("Windows")!=-1)&&((navigator.userAgent).indexOf("Firefox")!=-1)){
document.write('<link rel="stylesheet" type="text/css" href="css/w3_pc.css">');
}

if (screen.width >800){
document.write('<style type=\"text/css\">body{background-image: url\(images/_welcome/welcome_bg.jpg\)\;layer-background-image: url\(images/_welcome/welcome_bg.jpg\)\;\}<\/style>');
}
else {
document.write('<style type=\"text/css\">body{background-image: url\(images/_welcome/welcome_bg2.jpg\)\;layer-background-image: url\(images/_welcome/welcome_bg2.jpg\)\;\}<\/style>');
}