Refactor CSS

[shellyear]

Hi, @blcham ! I would like to start a discussion here about CSS things that needs to be changed in the project, and that were not included as part of this merged PR

Overall styles look good, but I would like to discuss the usage of

this font in the project (as it was initially in the project).

Also I would like to get rid of the css classes, if the project will have a tension to grow in the near future. But if the project will not grow in size(significantly), keeping styles in one css file seems to be beneficial, but I still see the need to use styled components/emotion or just LESS/SASS to organize the styles better, to make them modular. Plain css can be just used to define the very basic things like importing fonts, setting default font-size, defining color palette etc.