title: css triangle mask
body: <p>I would like to create a theme for tumblr where two images are overlayed to appear as one image. The two images would be positioned one on top of the other with the top image masked in the shape of a triangle.</p>
  
  <p>Here is a photoshop mockup of what I am hoping to achieve: <a href="http://s3.amazonaws.com/data.tumblr.com/tumblr_l6w6w3sdM51qa49m9o1_1280.png?AWSAccessKeyId=0RYTHV9YYQ4W5Q3HQMG2&amp;Expires=1298329479&amp;Signature=cUcRVwOWEp6m%2BDDnJgTs81rhPxA%3D" rel="nofollow">http://s3.amazonaws.com/data.tumblr.com/tumblr_l6w6w3sdM51qa49m9o1_1280.png?AWSAccessKeyId=0RYTHV9YYQ4W5Q3HQMG2&amp;Expires=1298329479&amp;Signature=cUcRVwOWEp6m%2BDDnJgTs81rhPxA%3D</a></p>
  
  <p>The only bit I am unsure about is the masking of the triangle image. Not sure if it is possible... Any ideas?</p>