On Windows 10 and macOS, we should be able to set the browser theme independently of the system theme. There are certain scenarios where I might want my system to follow a dark theme but some apps to follow a light theme (for example, email and websites tend to be white to a light theme makes the UI less jarring and improves the reading experience, in my opinion). There may also be scenarios where I want a light-themed system with a dark-themed browser. The user should be free to make these choices.
