Change the color of the caption. You can also write you own style rules within the caption to acchieve this.

    <div class="demo" id="container">
        <ul>
            <li>
                <a href="#"><img src="img/1.jpg" title="this is a normal caption" /></a>
            </li>
            <li>
                <a href="#" >
                <img src="img/2.jpg" title="<h3 style='color:yellow'>custom the caption</h3><hr/><p>with html, you can put link, button or any other element you want </p>" />
                </a>
            </li>
            ...
        </ul>
    </div>

     $(function() {

         $('#container').sliphover({
             fontColor: '#d14'
         });

     })