Mobile problem

Hello!

I have a test site (https://testi73.avaruus.net/). I have created a child theme to where I have copy-pasted some style css and changed font and background colors.

I have looked at the site with Nokia Lumia 620 and Samsung Galaxy S2 and the site is broken with mobile devices. I cannot use the navigation and the widget area is on the left and barely visible.

Please can someone help?

Best regards
Satu from Finland