General

Enable dark mode is the master switch, and the first thing on the screen. With it off, your site stays in its normal colours for everyone and nothing at all is added to your pages. Your settings are kept.

Default Mode is whichever their device says, by default. Somebody whose phone is in dark mode has already told it what they want, and asking again is a worse answer than acting on it.

Automatic Switching adds a schedule: between set hours, or from sunset to sunrise. Set hours are read from the reader's own clock, not your server's — so a reader in Sydney looking at a shop in Berlin gets dark at eight in the evening in Sydney. Sunset to sunrise uses the latitude and longitude you give, so it follows the sun at that place: give your own location, or wherever most of your readers are. The plugin never asks a visitor where they are. Leave the coordinates empty and it follows each visitor's device setting instead — which, on a phone set to switch automatically, is its own sunset.

A schedule only decides for somebody who has not chosen. The moment a reader presses the switch, their choice wins. How long it keeps winning is up to you, under How long, below.

Remember visitor's choice keeps their choice in their own browser — not a cookie, so it never travels with a request and never reaches your server.

How long it is kept has two answers:

• Until their device or your schedule next switches — the default on a new site. With a schedule (set hours, or sunset to sunrise at your coordinates), the choice ends at the schedule's next switch after the press, whether or not the reader has a page open then: dark pressed at 7pm on a site that goes dark at 8pm ends at 8pm, and the next morning the site is light again. With no schedule and Default Mode on Auto, their device decides, and a switch of the device can only be seen on a page: the choice ends the first time they open a page, or have one open, while their device is set the other way from when they pressed. A phone that goes dark and back to light while none of your pages is open leaves the choice as it was. Its ending is not a press, so usage statistics do not count it. A reader who wants dark all the time on a phone that switches by itself will need to press again after each switch. With Default Mode set to Light or Dark and no schedule nothing ever switches, so a choice stays until it is changed. The same goes for a page set to open dark: moving to it or from it is not a switch.
• Until they change it — the choice stays until they press the switch again, and from then on the schedule and their device never decide for them. A site that had the plugin before this setting keeps this, and its Dashboard offers the other answer once, with a button to switch it on.

It is decided in the reader's browser, before the page is painted, so a page cache serves everybody the same page and nobody sees a flash of the wrong colours. A choice kept from before, or made under Until they change it, lasts until it is changed whichever you pick later. ?dark=1 counts as a choice, and lasts the same way.

Sync to user account does the same thing one level up, for a membership site or a shop: a signed-in customer who chooses dark on their phone finds your site dark on their laptop. Off by default, because a site with no accounts should not pay for a feature it cannot use. A choice that ends at your schedule's switch ends on every device at the same moment. One that ends when a device switches is judged by each device on its own: a laptop set to light does not end a choice made on a phone that was dark, and when it ends on one device, or they set it back to Auto, it is forgotten on the account, while a device that already had it keeps it until its own setting switches.