Fix responsive bug top navigation

Hi,

I have found and fixed a minor layout bug (responsive)

This is the situation before the fix:
![before](/uploads/55bf61a64fb49a763c5f8381bf46d390/before.png)

And this is the situation after the fix:
![after](/uploads/33ba091156d404e52c41f134121c59f0/after.png)

See merge request !3190