Child Theme style.min.css

I created a child theme for the responsive-mobile theme as instructed in https://wordpress.org/support/topic/creating-child-theme-5?replies=2

I changed the background color of .front-page .content-area {} in the child theme’s style.css file to a dark gray, but noticed in the mobile version, the background color still remained blue.

I assume the mobile version is reading off of the parent theme’s /css/style.min.css file, so in the child theme folder, I also created /css/style.min.css and changed the background color to gray there as well, but it’s still coming up blue.

Any ideas how to change the background color in the mobile version?