Minor correction to blog article layout.
Added blog article about Gravity prototype.
Created one CSS file per section.

So far, those files are empty, but rules from main.css will be moved to
them in time. This should make the CSS easier to manage.
Fixed: Image style for about page applies to blog.
Refactoring.

Moved CSS rules for blog to blog.css.
Refactoring.

Moved CSS rules for contact page to contact.css.
Fixed: List style.

The style rules intended for tags applied to all lists in the blog.
Minor correction to article layout.
Removed example articles.