<!--
//イメージの事前読み込み
if(document.images) {
 var imgs = new Array();
  imgs[00] = new Image; imgs[00].src = "images/btn01.jpg" ;
  imgs[01] = new Image; imgs[01].src = "images/btn01_o.jpg";
  imgs[02] = new Image; imgs[02].src = "images/btn02.gif" ;
  imgs[03] = new Image; imgs[03].src = "images/btn02_o.gif";

}
//画像書き換え
function chgimg(id, imgname) {
 if(document.images) {
  if(imgs[imgname]) {
    document.images[id].src = imgs[imgname].src;
  }
  else {
    document.images[id].src = imgname;
  }
 }
}
// -->