Improve navbar readability and add logo.

[iiloni-umd]

Hello Binari developers. I am a first time contributor, and my experience using React with Babel is limited.

One of the first things I noticed when visiting https://binari.dev is that the navbar text doesn't have optimal readability. To address this, I changed the font size and font weight of the navbar links.

Before (top) and after (bottom) of the navbar when the parallax effect is not active (i.e. the page is scrolled to the top)

Before (top) and after (bottom) of the navbar when the parallax effect is active (i.e. the page is scrolled down)

I hope these changes seem reasonable and actionable in your eyes. Since I am not very experienced using React, I understand that these changes may not use the best conventions. If you agree with the design change, please feel free to create a new PR implementing these changes with better programming conventions.

Note: This pull request has been opened for credit in a university course.