Fixed html validation issue.

Had stray <P> tags in my posts.  D'oh!!
Bourbon's mighty tasty

Prepros includes support for Bourbon, and I took advantage, as well as
slightly changing the darken-hover mixin for a configurable percentage.
"Impressum" is now "imprint"

Also, I rewrote it to make it shorter and less boring.
Removed stray line breaks and useless tags
Fixed 404 page title