Here I have an bootstrap 3 layout and as you can see when I change browser dimension it works well:
but when I try this on mobile I dont get version with .xs
clasess I get version with full screen like on normal browser domension screen.
What can be the problem? Bootstrap 3 or my mobile phone browsers?
Most likely, you need to add this to your head.
To be compatible with 'old' non-responsive websites, most mobile browsers automatically fake their screen to be larger, so that they can correctly display those sites. This meta tag prevents them from doing this.