Homepage mock-up

- [x] Persistent navbar
- [x] Customize font and homepage design
- [x] Setup folder hierarchy
We usually avoid referring by id in our CSS selector unless a special case because ID is always unique throughout the site, which means your style only works on one particular item, thus it makes CSS not reusable in different places. Use class selector instead.

For this case, `#text-large`, referring to a specific behavior rather than a specific component. So Behavior should be reusable, use class `.text-large` instead.