css – Position text inside ahref element (in center of image)

I created a static block with the following issue:

I’m trying to center text inside an ahref element, which looks like the following;

    <div class="small-24 medium-16 cell">
    <a title="Chairs" href="http://magento.stackexchange.com/chairs"><img src="https://magento.stackexchange.com/{{media url="wysiwyg/chair-1.png"}}" alt="Chairs" width="830" height="325">Chairs</a>
    </div>

Normally, I would position it as follows, with the text in a span in the ahref element next to the img:

a {
   position: relative;
}
span {
position: absolute;
bottom: 10px;
left: 10px;
}

However, I’m not allowed to save the span tag inside the ahref element next to the image. See image underneath.
enter image description here

How can I position the text inside the ahref element over the image?