Why is the spinner not spinning/rotating?

Question

I have created a anchor link button where I want to show Spinner animation when I click on button in :focus state. I'm using Font Awesome to show animation but when I click on the button, the spinner animation is not working.

Note: I don't want to use JavaScript here just want to do with Pure CSS

Here is the CodePen link https://codepen.io/rhulkashyap/pen/vLPNdQ

@import url(https://fonts.googleapis.com/css?family=Titillium+Web);
 body {
  font-family: 'Titillium Web', sans-serif;
  text-align: center;
}
#button {
  padding: 15px;
  background-color: green;
  color: #fff;
  text-decoration: none;
  border-radius: 5px;
  width: 300px;
  display: inline-block;
  text-align: center;
  font-size: 25px;
  -webkit-transition: all .3s ease-in-out;
  transition: all .3s ease-in-out;
}
#button:before {
  content: "\f090";
  font-family: FontAwesome;
  margin-right: 5px;
}
#button:focus {
  background-color: #02b402;
}
#button:focus:before {
  content: "\f1ce";
  -webkit-animation: spin .8s ease infinite;
  animation: spin .8s ease infinite;
}
@-webkit-keyframes spin {
  from {
    -webkit-transform: rotate(0deg);
    transform: rotate(0deg);
  }
  to {
    -webkit-transform: rotate(359deg);
    transform: rotate(359deg);
  }
}
@keyframes spin {
  from {
    -webkit-transform: rotate(0deg);
    transform: rotate(0deg);
  }
  to {
    -webkit-transform: rotate(359deg);
    transform: rotate(359deg);
  }
}

<link href="https://maxcdn.bootstrapcdn.com/font-awesome/4.5.0/css/font-awesome.min.css" rel="stylesheet" />
<h2> Click Here</h2>
<a id="button" href="javascript:void(0)">Enter In</a>

Answer 1

Transforms are supposed to work only on block level elements (including inline-block). Making the pseudo-element as display:inline-block makes the animation work.

After commenting on the question, I did see that the animation wasn't working in Chrome v50 (dev-m) also while it was working in Chrome v43. So, the current behavior seems to be consistent

@import url(https://fonts.googleapis.com/css?family=Titillium+Web);
 body {
  font-family: 'Titillium Web', sans-serif;
  text-align: center;
}
#button {
  padding: 15px;
  background-color: green;
  color: #fff;
  text-decoration: none;
  border-radius: 5px;
  width: 300px;
  display: inline-block;
  text-align: center;
  font-size: 25px;
  -webkit-transition: all .3s ease-in-out;
  transition: all .3s ease-in-out;
}
#button:before {
  display: inline-block;
  content: "\f090";
  font-family: FontAwesome;
  margin-right: 5px;
}
#button:focus {
  background-color: #02b402;
}
#button:focus:before {
  content: "\f1ce";
  -webkit-animation: spin .8s ease infinite;
  animation: spin .8s ease infinite;
}
@-webkit-keyframes spin {
  from {
    -webkit-transform: rotate(0deg);
    transform: rotate(0deg);
  }
  to {
    -webkit-transform: rotate(359deg);
    transform: rotate(359deg);
  }
}
@keyframes spin {
  from {
    -webkit-transform: rotate(0deg);
    transform: rotate(0deg);
  }
  to {
    -webkit-transform: rotate(359deg);
    transform: rotate(359deg);
  }
}

<link href="https://maxcdn.bootstrapcdn.com/font-awesome/4.5.0/css/font-awesome.min.css" rel="stylesheet" />
<h2> Click Here</h2>
<a id="button" href="javascript:void(0)">Enter In</a>