Question Little annoying marging problem in Header

[MikaelB]

Hi,

I try to do what seems quite easy to do, but i'm not sure to do it in the correct manner.
i've done a little website in french for a little company.
In the header, i would like to have in the left : the NAME and just below 2 words as a slogan. the Name and the slogan has different heights.

The problem i have is that i can't arrive with one text case. So i create 3 columns for the header, one for the menu in the right, one for the NAME on the left, and in the center one more for the slogan. I then use the margin possiblities, to put the slogan just below the NAME of the site. It works quite well except a little annoying thing :

In responsive mode, for mobile, it gives a little marge in the header below.
You can see the attached files.

So my question is, is there a better method to do what i want ??

thanks a lot and excuse my poor english.