Some styling updates

[lynnandtonic]

This PR:

• Allows browser default :focus for anchors and buttons Allow links and buttons to have :focus styles #128
• Changes the .container to be full-width with a default max-width: 960px Change width of .container to have just a max-width #127
  • I figure we will probably override this in each site when needed
• Removes the recommendation that the <h1> be a container for the logo
• Gives some better spacing for lists and nested lists
• Changes font sizes from px to rem and em where makes sense
• Some cleanup

[DianaPerkinsDesign]

@lynnandtonic LGTM! Admittedly, it's hard to say without taking it for a test drive, but I read through everything and it looks good!

[lynnandtonic]

@DianaPerkinsDesign Awesome! Thanks for taking a look. After we cut a new version I’ll get it into andyet.com and we can see if anything feels off or missing.