Theme not rendering correctly on mobile

Hi amazing people
I am new to ghost and I have just created my new satirical parody publication Xivilization.org, making fun on the Chinese president for life Xi Jinping.

I have used the default Ghost template, and set background color to Black (#000000). The theme renders as expected on desktop, which you can verify at https://xivilization.org.

However, on mobile the backgroudn color is inexplicably and consistently rendering as White (looking like #FFFFFF) across different browsers (Edge and Vivaldi), as shown in the screen capture below… I have done some digging around on the forum and official docs to no avail.
Anyone have an idea?

Thanks in advance!

Technical details:

Version: [5.108.1-0-g3e2658ba+moya]
Newest as of 01/Feb/2025

Site url: https://xivilization.org