.img-caption {display: inline-block; position: relative;}

.img-caption:after {
    content: attr(data-caption);
    position: absolute;
    left: 0;
    right: 0;
    bottom: 0;
    z-index: 1;
    background: #00000099;
    color: #fff;
    font-size: 0.9rem;
    padding: 15px 30px;
    opacity: 0;
    -webkit-transition: opacity 0.3s linear;
    transition: opacity 0.3s linear;
	-o-transition: opacity 0.3s linear;
}

.img-caption:hover::after {opacity: 1;}

a.img-caption img {display: block;}