Help ME HEADER PROBLEM

Question

How to make header fit the screen and not leave left or right space

code:https://code.sololearn.com/WpHWjl5SJB4O/?ref=app

Answer 1

Getting rid of white edge :
https://code.sololearn.com/WyGa6Wh1V96b/?ref=app

from tutorial by Gordon :
https://code.sololearn.com/W3gS00IGw160/?ref=app