This Safari add on gives you the option to turn the white background on all websites into a completely black, which looks great on OLED and significantly reduces eye strain. This is the best dark mode enabler for Safari I’ve tried. There’s one bug though that the developer should fix: when you install this add on in Safari preferences, instead of it just having one toggle for all websites there’s two toggles: one for some weird sales force website, and another for other websites. These should be consolidated into the same toggle.