Help with border and padding

[Porphyrogennitos]

CodePen.

I want these:

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:

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

[Porphyrogennitos]

Can someone help me?