[jQuery] Changing Tooltip style

[apple]

Hi,

I would like to change the tooltip style: making the font smaller with
a different color ; I tried changing the tooltip.css but it seems not
to work...

#tooltip {
        position: absolute;
        z-index: 3000;
        background-color: #eee;
        padding: 5px;
        font-size:small;                     <-----
        opacity: 0.85;
}


Please advice.

Thanks in advance