window.onload = function () {
    var header = document.getElementById('imglogo');
var d=new Date();
var month=new Array(12);
month[0]="January.png";
month[1]="February.png";
month[2]="March.png";
month[3]="April.png";
month[4]="May.png";
month[5]="June.png";
month[6]="July.png";
month[7]="August.png";
month[8]="September.png";
month[9]="October.png";
month[10]="November.png";
month[11]="December.png";
    if (document.images) {
        var chosenPic = d.getMonth();
        header.style.background = 'url(../Themes/cracked/images/img/months/' + month[chosenPic] + ')  no-repeat';
    }
}