CSS sprites for buttons

Found these login buttons online which have three states - normal, hover and visited. This makes them perfect to use as a CSS sprite, so here's how that went down:

The CSS looks like this:

.signin_button {
  display: block;
  height: 22px;
  width: 150px;
  font-size: 0.1em;

#twitter_button {
  background: transparent url(/images/signin_twitter.png) top left no-repeat;

#facebook_button {
  background: transparent url(/images/signin_facebook.png) top left no-repeat;

#facebook_button:hover {
  background-position: 0px -24px;

#facebook_button:active {
  background-position: 0px -48px;

span.hide {
  display: none;

and the HTML looks like this:

  <a class="signin_button" href="/oauth/create" id="twitter_button">
    <span class="hide">
      Sign in with Twitter.
  <a class="signin_button" href="/oauth/create" id="facebook_button">
    <span class="hide">
      Sign in with Facebook.

Note: `display: none;` is a no-no in terms of accessibility, but after the first couple accessibility-friendly attempts failed, I got lazy. Perhaps I should pursue a JavaScript solution, as I **believe** that screen readers interrupt the page pre-JS.