when I compare the original «Module Style Overrides» section (installed on my testing website) with the same section (installed on my client's website) there are some differences which I do not understand.
Original installed on my testing website
Copy installed on my client's website
I copy&paste the background image «images/homepage/module-bg1.jpg» and this becomes «images/homepage/module-bg1.jpg#joomlaImage://local-images/homepage/module-bg1.jpg?width=642&height=346».
I copy&paste the background color «#968679» and this becomes «rgba(150, 134, 121, 1)»
There can often be seen, that Joomla automatically adds some kind of appendix to the selected image path. But sometimes it does not.
Furthermore, on your demo website the three modules in position top-1 have a thin white border. On my test website it does not. Although this is an untouched website installed by using the J51_Serenity demo installer.
Thank you very much and kind regards
Chris