Image behind the slider on SweetHome

HI,

I have the "sweethome" theme, I made some changes but I have a main issue with the image behind the slider (I took the slider of by the way). I change the image but when I want to see the site on a responsive way the sise of this image does not change...
Here the link to the site:

http://johannehomemanagement.com/

Maybe I´m doing something wrong or I´ve remove something on a wrong way...

Thanks in advance for your help!
Regards