blog/article background image on App

Hello,Currently the android app fetches default website background ( base template ) while displaying blogs/article page on android - I want to specify different background for both modules but only for android and not the web version(it should inherit for base). Can someone help please? 

You need to modify mobile.css in your template. The base css is templates/base/css/mobile.css

The class to override:

.bx-sys-mobile-page {
    padding:0;
    margin:0;
    background-image: url(../images/sys-bg-main.png);
}

 Thank you Alex.. :)