title: How to change color of png on hover?
body: <p>I made a "down arrow" in illustrator and saved it as a png with a transparent background. When I put it into my webpage as an img, it shows up in the original color, which is okay. 
  I'm trying to do </p>
  
  <pre><code>  img:hover{color:red;}
  </code></pre>
  
  <p>and it doesn't work. </p>
  
  <p>Does anyone know how to make it work?</p>
  
  <p>Thanks</p>