Where's the Class Go?

There was a debate at work the other day concerning where to place a class on a given snippet of HTML. The HTML was used to markup a linked profile photo and the disagreement was whether or not to place the class on the anchor or the image tag. The markup is:

div class="nr-comment-reply"
  a href="#"
    img src="http://placehold.it/100/100"

The CSS is:

.c-avatar {
  display: block;
  float: left;
  border-radius: 19px;
  width: 38px;
  height: 38px;

Since the avatar link and image combo is floated to the left, placing the class on the image removes the anchor element from the DOM. This wouldn’t appear to be a problem if you were fine removing focus on the entire element when tabbing through the page. For example: http://cl.ly/fFwI

The benefit of placing the CSS class on the anchor element is it keeps tab focus on the entire element as seen here: http://cl.ly/fFxh

Long story short: Put the class on the anchor tag if you care about tab focus.