I need your help :)

Question

( sorry for my english )

Imagine I want to make a webpage header, i wont that takes all the width, but I cant it when it’s a « background-color:; » and I do « margin:-8px; » like in this code :
https://code.sololearn.com/WWXaD4i3Slo8/?ref=app

And the other problem is that I don’t know to put 2 elements on only one Line

If you could help me, thanks <3

Answer 1

Second answer:
display: inline / inline-block

or

display: flex; (parent)
flex-direction: row; (children)

Answer 2

Do you know about display property of CSS??