On my Tumblr page, when a user click on my image, I want the image to enlarge. Click here for an example of a Tumblr page that does what I want. The Image enlarges once its being clicked on, and it returns back to the Tumblr page when the user clicks on the area that isn't the image.
I tired searching for a solution for a few days now, but nobody that I know seems to know how to do this.