Adds nicer whitespace to definition desciption tags in base.css.
Adds minor improvements for the ribbon styling.

 - Adds a nice glow to the text on hover/mouseover.
 - Removes any background or styling that might have been added by other rules.
 - Adds the ability to make the ribbon fixed instead of absolutely positioned.
Improvements to index.html

 - Adds a link to the base.css file.
 - Puts the content in a <DIV> tag so it works nicer with the base style.
 - Adds a link to the cascade.html file, commented out untill that document is complete.
 - Adds a github ribbon, closes #3.