How do I display title in a slide gallery?

When I setup a photo gallery, how can I force it to show the title on hover? I tried this CSS but it no longer works:

    /* This displays the Title */
.sqs-gallery-design-grid-slide:hover :after {
content:attr(data-title);
font-family: proxima-nova, sans-serif;
font-size: 12px;
display: block;
text-align: center;

}
/* This make the gap between the images a little bit bigger */
.sqs-gallery-block-grid .sqs-gallery-design-grid-slide .margin-wrapper {
margin-bottom: 30px !important;
}

Thanks!