sfHover = function() {
    var sfEls = document.getElementById("nav").getElementsByTagName("LI");
    for (var i = 0; i < sfEls.length; i++) {
        sfEls[i].onmouseover = function() {
            this.className += " sfhover";
        }
        sfEls[i].onmouseout = function() {
            this.className = this.className.replace(new RegExp(" sfhover\\b"), "");
        }
    }
}
if (window.attachEvent) window.attachEvent("onload", sfHover);

function changeCSS() {
    var elementChange = document.getElementById('DH');
    elementChange.style.className = elementChange.style.className.replace('unhighlighted', 'highlighted');
}
function changeCSSback(csselement) {
    document.getElementById(csselement).className = document.getElementById(csselement).className.replace(/\bhighlighted\b/, 'unhighlighted');
}