The folks over at Linus Tech Tips (or one of the associated channels, can’t remember which) did a bit on dark mode recently, and they mentioned an extension for Chrome and Firefox called “Dark Reader” which dynamically darkens up webpages as you browse to them. I’m a Firefox user for personal stuff, so I loaded it up and it works great on all the sites I routinely browse, including Thurrott.com. Because Firefox for Android can use the desktop extensions, it works on my Galaxy S7 too, very nice. You can turn it off per site and change a few other visual parameters to your own liking. If you’re interested, it’s in the regular Firefox add-on store.
EDIT: Thought I’d add a correction, I prefer the native Outlook.com dark mode after fiddling around a bit, so I disabled it for that site. However, I added it to the installation of Vivaldi I use to access SharePoint and our enterprise systems at work, and it is fantastic. Not a hiccup, and it looks wonderful.