//ブラウザがPNG形式ファイルに対応しているかどうかをチェック
function BrowserCheck(){
      if(navigator.appName=="Microsoft Internet Explorer"){
        if(navigator.appVersion.indexOf("Win")<0){
          if(navigator.appVersion.indexOf("4.")<0){
            return true;
          } else{
            return false;
          };
        } else{
         return true;
        };
      } else{
       return true;
      };
};
function writeTitle(pngfile,altname,size){
      if(BrowserCheck()){
        document.write("<img src='./images/",pngfile,"' alt='",altname,"' >");
      } else {
        document.write("<FONT size='",size,"' color='aqua'><I><B>",altname,"</B></I></FONT>");
      };
}
function writeButton(pngfile,altname,size){
      if(BrowserCheck()){
        document.write("<img src='./images/",pngfile,"' alt='",altname,"' >");
      } else {
        document.write("<FONT size='",size,"' color='gold'><I><B>",altname,"</B></I></FONT>&nbsp");
      };
}