Simple color change

## Changes
Changed the main color found in the menu-nav from the stark yellow to a new teal color pulled out of the header image to bring a cohesive color flow to the page. To do this I created a new variable inside the _variables partial and simplified the button by adding a transparent background to them allowing the color behind to show through.

## Thanks
I hope you will consider these changes for your project, I think they will really punch the menu-nav up a notch and make the project more successful.

-Jesse