Some scores render ok in both light or dark mode

Some scores seem to display correctly in both light or dark mode on musescore.com. Others don't.

For instance, this score displays correctly in both:
light_or_dark_mode_ok.mscz
https://musescore.com/user/29785346/scores/5341926

However, this one only displays correctly in light mode - in dark mode it renders all white:
light_mode_ok_only.mscz
https://musescore.com/user/10226856/scores/6452520

I wonder, what is different in the first score that makes it display correctly in both modes? Is there some setting to make the canvas background transparent, which causes the background color to flip automatically from white to black when in dark mode, and vice versa? Thanks