function hover(id, imgId, newImgId) {
    document.getElementById(id).className = "sfhover";
    replace(imgId, newImgId);
}
function nohover(id, imgId, newImgId) {
    document.getElementById(id).className = "";
    replace(imgId, newImgId);
}
function replace(id, newId) {
    document.getElementById(id).style.display = "none";
    document.getElementById(newId).style.display = "";
}
function swap(id, newImg) {
    document.getElementById(id).src = newImg;
}