(function (menu) {

  var img = menu.getElementsByTagName ('img');


  for (var el, i = img.length; i--;)

    if (!(el = img[i]).src.match (/\-on\.gif$/)) {

      new Image ().src = el.src.replace (/\.gif/, '-over.gif');

      el.setAttribute ('data-base', el.src);


      el.onmouseover = function (ev) {

        this.src = this.getAttribute ('data-base').replace (/\.gif/, '-over.gif');

      };


      el.onmouseout = function (ev) {

        this.src = this.getAttribute ('data-base');

      }


      el.onclick = function (ev) {

        window.location = this.getAttribute ('data-base').match (/([^\/]*)\.gif$/)[1] + '.html';

      }

    }

}) (document.getElementById ('menu'));