function changeTextSize(selector, amount, type) {
    var size = $(selector).css("fontSize");

    if (!type) type = "%";

    if (size == "" || size.indexOf(type) < 0) {
        size = 100;
        type = "%";
    } else {
        size = parseInt(size.replace(type, ""));
       
    }
    
    if (amount) {
        size += amount;
    } else if (originalTextSize) {
        size = originalTextSize;
    }
    if (size > 20) {return false;}
    $(selector).css("fontSize", size + type);
}