I was looking over Winter Bash 2020 on the Stack Exchange site. I noticed the following hat and requirement:
Try Dark Mode
When you click about this hat the description says:
Have Dark Mode enabled and visit a page on Stack Overflow in English, Japanese, Portuguese, Russian, or Spanish.
If you go to your user preferences on Stack Overflow under theme you can choose dark. It should look something like this:
It looks like this function is only available on Stack Overflow. But, I'm assuming this is something that could later roll out on all @ SE sites.
What does Chinese @ SE think? Is this something we would like?