This is the stderr looks like

prince: -:style:2: warning: unknown property 'color-scheme'\nprince: -:style:2: warning: unknown property 'supported-color-schemes'\nprince: -:style:2: warning: unknown property 'behavior'\nprince: -:style:161: warning: unknown media feature 'prefers-color-scheme'\nprince: -:style:62: warning: unknown media feature 'prefers-color-scheme'\n\n*** Mercury runtime: caught strange segmentation violation ***\nPC at signal: 139740655820761 (7f17e8269fd9)\nThis may have been caused by a stack overflow, due to unbounded recursion.\n

Would you be able to attach or email me (mikeday@yeslogic.com) the HTML + CSS that causes the problem? It's unlikely to be related to the color-scheme property, that's just a warning about a property that Prince currently doesn't support.

This issue related to a potential crash at program exit if background threads make HTTPS requests using OpenSSL, and has been fixed in the latest build, thanks for letting us know!