Tweaks for BPTBT

Main things are:
- Blue theme for calendar
- new color for the tapered-arrow-up
- Default args in lightbox.

This is how the blue calendar looks
![screen shot 2014-08-29 at 12 20 30](https://cloud.githubusercontent.com/assets/1152640/4089044/24390310-2f66-11e4-9f4c-a84d45aa3f6e.png)

Use the mixin/extend