fix: Setting explicit Typography components to fix invalid DOM (#25)

* fix: Setting explicit Typography components to fix invalid DOM

Typography, by default, uses <p> as it's underlying component. When used
to embed other components it resulted in a DOM errors like: "<p> cannot appear
as descendant of <p>"... and more.

fix: Linting

* chore: apply suggestions from code review

Co-authored-by: Vojtech Simetka <vojtech@simetka.cz>

src/components/NavBar.tsx

@@ -1,7 +1,7 @@
 import React, { useState } from 'react';
 
 import { createStyles, Theme, makeStyles } from '@material-ui/core/styles';
-import { AppBar, Toolbar, Chip, IconButton } from '@material-ui/core/';
+import { Toolbar, Chip, IconButton } from '@material-ui/core/';
 
 import { Sun, Moon } from 'react-feather';