From the WebKit blog:

In the spring of 2019, Safari 12.1 became the first browser to support dark mode on the web. A lot of people love using dark mode, but not every website has a dark version. Almost 40% of web page loads are from users in dark mode, and yet only 10% of page loads support it. If you love dark mode, you’ve probably hit a site that felt particularly bright. Adaptive Dark Mode is designed to close that gap, providing a consistent dark experience across the web.

You can try it today in Safari 27.3 beta. To enable, first make sure your system appearance is set to dark. Then browse to a website with a bright background. Safari will offer a preview of Adaptive Dark Mode. Tap ‘Try’.

For websites that signal support of dark mode with <meta name="color-scheme" content="light dark"> in HTML or color-scheme: light dark in CSS, Adaptive Dark Mode does not change a thing. For the rest of the web, it quickly analyzes the page, looking at colors and estimating whether it’s predominantly light or dark. If the page generally has a dark background with light text, nothing is changed. When a page has a light appearance, Adaptive Dark Mode adapts the page to be dark.

For years, I’ve used Noir to force a dark mode onto websites that don’t support it. It is a great app, but even great apps can’t overcome web design that doesn’t seem to consider dark mode at all, like Apple’s own website:

Dark Mode Noir

WebKit’s implementation seems to have similar issues. Here is the same page, on an iPhone Air running iOS 27.3:

Dark Mode Safari

Clearly, this isn’t perfect, but for a lot of people, it should be better than using the web without an extension like Noir.

Jason Snell wants to see Apple push this harder:

This is a great feature that’s long overdue as a part of Safari. But Apple needs to not stop here: HTML email in Apple Mail is also a disaster in dark mode. Also, this change doesn’t affect in-app WebViews today, which means your in-app browser sheet will still shout at you in the dark. Once this shakedown cruise in Safari is done, Apple needs to put these smarts everywhere.