When editing ANY CSS, the .x-containerrule vanishes because cs-theme-options-generated-inline-css vanishes from the DOM. I’ve recorded a gif to help demonstrate it.
In the GIF I am demonstrating that .x-container defines the max-width of the container, and that cs-theme-options-generated-inline-css is the source of this, shown in the Sources tab. And then when I simply make ANY edits to the CSS (in this case, I simply add a space) it removes the entire block in the DOM for cs-theme-options-generated-inline-css which effectively removes .x-container - which then bugs up the view and I cannot accurately work on our site.