Update mobile responsiveness + design

[jeannienguyen]

Description

• updated responsiveness for all devices
• had to refactor about section in order to properly display website on mobile view
• refactored header and footer for responsiveness

Fixes issue #147.

Type of Change:

• Code
• User Interface

Checklist:

• [x] My PR follows the style guidelines of this project
• [x] I have performed a self-review of my own code or materials

[anubhavpulkit]

conflicts

[anurag4499]

shall I do it