Background color in resized menus

When I browse my page in my computer, the color scheme works OK.
But when I try to do it in my phone (or using te Responsive Layouts option in the Web Developer plugin), the colours of the menu change…
It should be Brown color in the back, lighter brown when I browse. Instead of that, I get a big brown stripe and then the menus in black & grey

Can any body help me??
Thank you!!!

PS: BTW, my web (as it is now): http://www.expedicionesitaca.es/