Changed the color of highlighted props in CSS

Fixes #15

Before:
![](https://photos-5.dropbox.com/t/0/AAA3QnuthDQvjs7AhvnCvlm0xncwLbCl-jdijb8HrpR_jw/12/97752/png/1024x768/3/1401181200/0/2/Screenshot%202014-05-27%2009.49.03.png/wjUPgWGMFeQS6GnqnZbs3pqGZdZWgj8I8LZWKpddMyk)

After:
![](https://photos-5.dropbox.com/t/0/AABFiE27_z7G7ChRzSyMB8A97vSpXcojwbSFIOuzFApuRQ/12/97752/png/1024x768/3/1401181200/0/2/Screenshot%202014-05-27%2009.48.39.png/JslfBy9BQzM7zCkN18ni_UMUJnfpYmqihGCbiVvScyc)