Help with border and padding

CodePen.

I want these:

Screenshot 2021-02-25 121528

To be at the beginning of the screen. If I remove the padding-left from the navbar, it will work, but I don’t want to.

Also, notice:
Screenshot 2021-02-25 121528

The border-top doesn’t collide with the border-left. How can I fix that?

Can someone help me?