Fix issue #28 color of `p code`

Would it look better with theme color?

After:

![screen shot 2013-11-17 at 12 13 03](https://f.cloud.github.com/assets/43471/1557955/c6580276-4f52-11e3-83b4-10f5ef8c4f43.png)

Before:

![screen shot 2013-11-17 at 11 24 34](https://f.cloud.github.com/assets/43471/1557956/c8a66c7a-4f52-11e3-8d88-fd5e75a6aaf2.png)