function buttonOver(elementId, height) {
    document.getElementById(elementId).style.backgroundPosition = "0px -" + height + "px";
}

function buttonOut(elementId, height) {
    document.getElementById(elementId).style.backgroundPosition = "0px 0px";
}

function buttonUp(elementId, height) {
    document.getElementById(elementId).style.backgroundPosition = "0px -" + height + "px";
}

function buttonDown(elementId, height) {
    document.getElementById(elementId).style.backgroundPosition = "0px -" + (2 * height) + "px";
}

function tabOver(elementId) {
    document.getElementById(elementId).style.backgroundPosition = "0px -21px";
}

function tabOut(elementId) {
    document.getElementById(elementId).style.backgroundPosition = "0px 0px";
}