Mobile tweaks

**Status:**
:+1: Ready for merge. :+1: 


**Changelist:**
* Added header menu to homepage
* Increased font size and line height
* Adjusted post column from 6 to 8.
* Removed tagline on navigation
* Made the header not shrink after scrolling down if you're on a mobile view.


**Known issues (to fix before merge):**
* <del>Active class is applied to every link in the mobile header on the homepage.</del> [Fixed.](https://github.com/l1f7/l1f7.github.io/commit/0dbf1e2c7883b8e8914deff459d5c0c9f6874943)
* <del>Text on homepage needs to be capped at a certain size to prevent the navigation from being hidden.</del> [Fixed.](https://github.com/l1f7/l1f7.github.io/commit/eabf177094de5a716f1f485ea346e48c6eecc3fd)