Johan Fredrik Varen

Dharmen Shah Thanks, but I tried that. Chrome seems to always first draw a white viewport unless it has the dark mode CSS already cached. I ended up with backend rendering like I said, with a cookie to hold the state instead of local storage. Works flawlessly in practice, but it feels old-school and I wish your approach would have worked as I think it's a more appropriate SoC fulfillment.

This is a beautiful way of doing it, except for the one major flaw: The flash of light-mode at every page (re)load. I've tried several approaches, but as long as you set the dark-mode stylesheet URL using JS you'll either have a bright flash of unstyled content or a bright flash of light-mode content. This is even visible in the GIF shown in this article. I'm afraid I've no choice but to ditch this approach and resort to backend rendering.