This is an obscure one. I have a client that uses this combination for their business. RW Elephant put out their new plugin v2x rather than update their old v1x plugin, and it’s basically like starting over. Honestly, configuration worked pretty well, but there were some problems. Firstly, it defaulted to full browser width on its primary inventory screens, which looked like poop. This was fixed by heading to their rw-elephant.min.css in wp-content\plugins\rw-elephant-retail-inventory\lib\assets\css and changing the .rwe-inventory margin setting to auto and width to 80% in order to shrink and align the inventory content.
The second, uglier issue was how the single item page presented itself. The plugin seems to present single items in a dynamically generated WordPress Posts style using the default posts setting. In this case that meant adding a right-hand links column that wasn’t wanted as well as an unnecessary posts header, and it squished everything, site header, content and all, into a left justified container. I found this page on Elegant Themes that covers removing the sidebars, but it proved insufficient. The header content, which was full width throughout the site, was still bordered, and the poet header remained.
Ultimately this was all fixed by following their procedure of creating custom templates. However, instead of copying single.php from the Divi theme directory into single-item.php in the new template directory, page.php was copied from the Divi theme dir and renamed to single-item.php (the same page.php the instructions say to copy and rename to gallery-page.php). This forced the plugin to retain the same settings found on all the other pages on the site for its posts styled page.
UPDATE: Since writing this post they pushed a plugin update which overwrites the aforementioned css file and sets the margins back to 0 and 100%.