That image does not seem to exist?
Use this code...
body {
background-image: url("/images/gallery/miller-pizza-company-chicago-storefront.jpeg");
background-size: cover;
background-attachment: fixed;
}
#rt-top-surround {
background-color: transparent;
}
This is how to create a custom CSS compatible with Gantry 4...
Simply create a file called "<TEMPLATENAME>-custom.css" and put this file in the CSS folder of the template (where <TEMPLATENAME> is the name of the template as seen in template manager e.g. rt_iridescent would be rt_iridescent-custom.css). GANTRY4 will automatically load this CSS file. If you wish, you can also have browser specific files by appending, for example, "-ie9" making the filename "<TEMPLATENAME>-custom-ie9.css"
Regards, Mark.