background image cover to whole page

I want to set image as my whole page background and also want to make it as responsive. I have tried:

CSS

background-image: url('../images/img1.jpg'); 
background-repeat: no-repeat, repeat;
background-size: cover;
-webkit-background-size: cover;
-moz-background-size: cover;
background-size: cover;
-o-background-size: cover;

but issue is still there when I open in small device; image was not set as per it was.

Please help me for this fix this issue