Updated .gitignore

Added other exceptions to .gitignore
Refined CSS styling

Adjusted CSS files to improve layout.
These changes were required to make the eos-help-center design play nicely with Yelp.

[endlessm/eos-sdk#2232]
Improved CSS formatting

Fixed some CSS code-styling errors. This is by no means a complete review of style and standard compliance.

[endlessm/eos-sdk#2232]
Merge pull request #3 from endlessm/sdk/2232

[endlessm/eos-sdk#2232]