Both Marcin and Lea are ignoring users who have automatic sunset-to-sunrise dark theme switching.

This is not a novelty but a built-in feature called “Auto” Appearance in MacOS, iOS, iPadOS. Similar feature exists in Android and KDE.

Imagine the user confusion when he sets the interface in light mode and a couple of minutes later this changes automatically to dark mode because sun sets.

As a user, I find the three "dark", "light", "auto" button situation way less complex then a toggle that keeps its state only if my choice does not align with system default.

New requirement just dropped: "Switch to light mode during more than 50% solar eclipse".

Well, that's pretty damned moronic, is what that is.

Even in the 1990s, developers of the HID specification knew that the keyboard pictured at the bottom of the article was wrong. They wrote in the power management spec that interface devices should conditionally send wake events, and that a dedicated wake key was not necessary. Microsoft said:

"For example, a keyboard could include a special-purpose power management button (for example, “Power”) that, when pressed during a system sleeping state, generates a wake event. Alternatively, the button(s) on mice and other pointing devices could be used to trigger a wake event. "

Letting the system do things for the user is risky enough. Taking away the unambiguous way to turn the automatism on and off just adds insult to injury. This suggestion is not simplification, it is complication.

Personally I'm totally fine with light/dark/auto but if you really must simplify I see only two true ways:

1. Just offer light and dark. No auto. Whether auto works is out of your control anyway. Users who know and want auto have to switch manually.

2. Just offer auto on/off. Default is off and off is light mode. User who want dark mode will figure out how to configure their system.

Why does every website even need to provide its own toggle in the first place? How often do people use these, really?

(I don't get the "everything needs to support dark theme" thing either tbh)

> One of the most common UX mistakes is designing UI around the underlying data model instead of user goals.

It's far worse to give the user a false mental model of the underlying system. If the underlying system is complex, but that's out of your control, then it will create confusion in users to paper over it. Please don't do this!

That is, unless you can create a leak-free abstraction. The example given in the article is anything but leak-free.

this all seems to fall into trap of most UI design writing, where people write blog posts about what users want, what users think, and what users understand, without actually doing any user testing.

unlike everybody else in this comment section, i like the two-mode toggle. but that's just my opinion. without user testing numbers, an article saying "users like this better" is useless.

But...there is a solution that works (although it may be a bit confusing at first). A toggle with two buttons, dark and light. Both cannot be pressed at the same time, but both can be unpressed at the same time. That's the auto mode, and the ui can be tweaked to show a little label in between or below.

In auto, none of the buttons is pressed (and preferable a small label that says auto is shown). Pressing dark/light will force that mode, enable that button and remove the auto label.

In dark/light mode, you can press the other button to enable the other state. Or you can press the current button to disable it, and switch to auto. This last one is the confusing-at-first interaction, but makes sense if you think about it.