function getCSS()
{
datetoday = new Date();
timenow=datetoday.getTime();
datetoday.setTime(timenow);
theMonth = datetoday.getMonth()+1;

if (theMonth == 4)
display = "http://www.taiheitenant.co.jp/css/bg1.css";
else if (theMonth == 5)
display = "http://www.taiheitenant.co.jp/css/bg2.css";
else if (theMonth == 6)
display = "http://www.taiheitenant.co.jp/css/bg3.css";
else if (theMonth == 7)
display = "http://www.taiheitenant.co.jp/css/bg4.css";
else if (theMonth == 8)
display = "http://www.taiheitenant.co.jp/css/bg1.css";
else if (theMonth == 9)
display = "http://www.taiheitenant.co.jp/css/bg2.css";
else if (theMonth == 10)
display = "http://www.taiheitenant.co.jp/css/bg3.css";
else if (theMonth == 11)
display = "http://www.taiheitenant.co.jp/css/bg4.css";
else if (theMonth == 12)
display = "http://www.taiheitenant.co.jp/css/bg1.css";
else if (theMonth == 1)
display = "http://www.taiheitenant.co.jp/css/bg2.css";
else if (theMonth == 2)
display = "http://www.taiheitenant.co.jp/css/bg3.css";
else if (theMonth == 3)
display = "http://www.taiheitenant.co.jp/css/bg4.css";
else
display = "http://www.taiheitenant.co.jp/css/bg1.css";
var css = '<'; css+='link rel="stylesheet" href=' + display + ' \/'; css+='>';
document.write(css);

}