Background images cut off when viewing it on Portrait mode on mobiles

Hello,

I was trying to find a solution to this problem on the forum but most of the open discussions were very specific and it was hard for me to find a simple solution to address this issue.

All I want is to make the background images fit to the portrait screen like how it is in landscape mode.

Here is what I am getting

Portrait mode: http://www.idime.us/wp-content/uploads/2016/05/KakaoTalk_Photo_2016-05-13-02-53-50_67.jpeg
Landscape mode: http://www.idime.us/wp-content/uploads/2016/05/KakaoTalk_Photo_2016-05-13-02-53-49_70.jpeg

What would be the solution for this problem?? I need your help desperately.

I don’t mind visitors having to zoom in all the time – I just want it to fit the screen so that viewers can see the whole images once they enter.