maxi=24;
mini=12;
step=2;
subject=".content";
dColor="#CCC";
eColor="#09C";
$.fn.getFontSize = function(){
    return parseInt(($(this).css("font-size")).replace("px",""));
}
$.fn.disableLink = function() {
    $(this).css({color:dColor,cursor:"default"});
}
$.fn.enableLink = function() {
    $(this).css({color:eColor,cursor:"pointer"});
}
$.fn.checkDisabled = function() {
    if($(this).css({color:dColor})||$(this).css({cursor:"default"})) return true;
    else return false;
}
$("#plus").click(function(){
    current=$(subject).getFontSize();
    if(current<maxi) {
        $(subject).css("font-size",current+step);
        if($("#minus").checkDisabled())
            $("#minus").enableLink();
    }
    if((current+step)==maxi) $(this).disableLink();
});
$("#minus").click(function(){
    current=$(subject).getFontSize();
    if(current>mini) {
        $(subject).css("font-size",current-step);
        if($("#plus").checkDisabled())
            $("#plus").enableLink();
    }
    if((current-step)==mini) $(this).disableLink();
});