title: change image on mouseover
body: <p>I've got a simple html/css page, where I show a picture.</p>
  
  <p>Now when the user moves the mouse on the picture, I'd like to swap out the picture to some other image.<br>
  Upon leaving the image area the old picture should be shown again.</p>
  
  <p>How can I achieve this? A version which works without javascript would be best.</p>
  
  <p>Thanks in advance!</p>