Step 1: When hovering over an image, add a shadow to it.
Step 2: When mouse leaves image, remove the shadow.
Step 3:
When clicking an image, replace Bill Murray with this picture: http://placecage.com/c/100/100, and change the opacity to all other images to 50%.
Step 4: Fix the hover rules so when you leave an image, all images reset to initial settings.
