.image-container {
        position: relative;
        display: inline-block;
    }

    .image-container img {display: block;}

        .image-container .after {
            display: block;

        }
        .image-container .after .content {
            position: absolute;
            background-color: #C0D8D8;
            bottom: 0;
            text-align: center;
            padding: 0px;
        }


<div class="after">
                <div class="content"><a href="<?php the_permalink(); ?>" title="<?php the_title_attribute(); ?>">this is some content. It can be long and span several lines.</a></div>
            </div>