[html] Can CSS3 transition font size?

How can one make the font size grow bigger on mouse over? Color transitions work fine over time, but the font size switches immediately for some reason.

Sample code:

body p {
     font-size: 12px;
     color: #0F9;
     transition:font-size 12s;
     -moz-transition:font-size 12s; /* Firefox 4 */
     -webkit-transition:font-size 12s; /* Safari and Chrome */
     -o-transition:font-size 12s;
     transition:color 12s;
     -moz-transition:color 12s; /* Firefox 4 */
     -webkit-transition:color 12s; /* Safari and Chrome */
     -o-transition:color 12s;
}

 p:hover {
      font-size: 40px;
      color:#FC0;
 }