Nalleto header on mobiles

Hi Guys, I’m working on the mobile version on my site and I’ve run into a small problem which I’m sure you’ll be able to assist me with.

In the mobile version, when I open my site I see a big logo on top and the menu below it. When I scroll down a bit, the navigation goes to the side which is how I ideally want it to be (sticky navigation)…When I´ve tried to modify it by css, the “div” which contains the logo changes but the logo has the same size… Could you please help me??

this is the link: http://tecsafer.com/