How to detect if the OS is in dark mode in browsers?

Similar to "How to detect if OS X is in dark mode?" only for browsers.

Has anyone found if there is a way to detect if the user's system is in the new OS X Dark Mode in Safari/Chrome/Firefox?

We would like to change our site's design to be dark-mode friendly based on the current operating mode.

The new standard is registered on W3C in Media Queries Level 5.

NOTE: currently only available in Safari Technology Preview Release 68

In case user preference is light:

/* Light mode */
@media (prefers-color-scheme: light) {
    body {
        background-color: white;
        color: black;
    }
}

In case user preference is dark:

/* Dark mode */
@media (prefers-color-scheme: dark) {
    body {
        background-color: black;
        color: white;
    }
}

There is also the option no-preference in case a user has no preference. But I recommend you just to use normal CSS in that case and cascade your CSS correctly.

EDIT (7 dec 2018):

In Safari Technology Preview Release 71 they announced a toggle switch in Safari to make testing easier. I also made a test page to see the browser behaviour.

If you have Safari Technology Preview Release 71 installed you can activate through:

Develop > Experimental Features > Dark Mode CSS Support

Then if you open the test page and open the element inspector you have a new icon to toggle Dark/Light mode.

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EDIT (11 feb 2019): Apple ships in the new Safari 12.1 dark mode

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EDIT (5 sep 2019): Currently 25% of the world can use dark mode CSS. Source: caniuse.com

Upcoming browsers:

• iOS 13 ( I guess it will be shipped next week after Apple's Keynote)
• EdgeHTML 76 (not sure when that will be shipped)

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EDIT (5 nov 2019): Currently 74% of the world can use dark mode CSS. Source: caniuse.com

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EDIT (3 Feb 2020): Microsoft Edge 79 supports dark mode. (released on 15 Jan 2020)

My suggestion would be: that you should consider implementing dark mode because most of the users can use it now (for night-time users of your site).

Note: All major browsers are supporting dark mode now, except: IE, Edge

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EDIT (19 Nov 2020): Currently 88% of the world can use dark mode CSS. Source: caniuse.com

CSS-framework Tailwind CSS v2.0 supports dark-mode. (released on 18 Nov 2020)

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EDIT (2 Dec 2020):

Google Chrome adds Dark Theme emulation to Dev Tools. Source: developer.chrome.com

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EDIT (2 May 2022):

Currently 90% of the world can use dark mode CSS. Source: caniuse.com

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EDIT (23 Jan 2024):

Currently 96.5% of the world can use dark mode CSS. Source: caniuse.com