Sass function improvement (list,loop, shared rules)

Hey,

I love what you've done with this project, it's very helpful to understand the css layout system. In this update, i've done two things:

1. I've updated the Sass function which is now using list and loop for a better sass flow.
2. I've also apply shared rules to every element at once (outline width/style) to avoid redundant css.

Sorry for the possible frenglish! Keep up the good work.

Salutations