2 file updates-1 better mobile optimization!

Created a new div class named "twitterbox" that will allow the Twitter feed to be centered (along with article h1s) when the site is 700px max. Had to change the index.html and the main css to include the div "twitterbox." 

The paragraphs stay the same. Since the twitter feed was originally looked at like the rest of the text, it was impossible to easily work on the twitter feed on CSS without changing the paragraphs as well. The div helped out a lot.

Hope you like the changes!