code-dot-org/code-dot-org — pull request #851 by islemaster (2014-12-12 01:19:54+00:00)
Title: #83716236: Match blocks proportional scaling of images

Solves [original request](https://www.pivotaltracker.com/story/show/83716236) to scale images in match blocks without changing aspect ratio. Also vertically centers images, and sets them on a white background with uniform colored borders for a cleaner look. Colors updated a bit to match [this color guide](https://s3.amazonaws.com/uploads.hipchat.com/65395/780341/kCxI5OwDMpdpdAz/Screen%20Shot%202014-10-14%20at%205.38.53%20PM.png). Tried to improve usability by adding a border color change and cursor change on rollover of an interactive tile, and adding a darker dotted outline to valid drop zones while dragging a tile.