Keep full page margin left/right when decreasing browser window

Hi,

I am having trouble with the left/right margin on my full webpage.

I have decided to not have a full width page, and when opening the website in a full screen webbrowser, everything is fine and the content is centered with space to both left and right side of browser window. But.. when I reduce the browser window, the margin decreases and the content ends up being full width with no margin. When i decrease further the website jumps to tablet mode where everything is fine again.

It is especially a problem with my header, where the logo has no space at all to the left side.

Can I somehow put a “minimum margin” to left and right side, making sure there is always some space between content and the sides of the browser window?

The page I need help with: [log in to see the link]