Robin Whittleton

Your EU ecommerce site legally requires a dark mode by the 28th June 2025

A couple of months ago I probably should have put a question mark on the end of that title, but the likelihood is tilting over in the direction of a full-stop.

First things first: why ? That’s the date the European Accessibility Act comes into force in each country in the EU. To be specific, the EAA is an EU directive: a requirement for each individual country to implement the directive as a local law. But the end effect is the same: there will finally be a legal requirement for accessibility in the private sector for a range of digital products and services, including banking, ebooks, travel tickets, and most importantly for me and my day job: ecommerce sites.

What does the EAA require?

Let’s take a journey through the legislation! As with all EU directives we can read it on EUR-lex, under its official title of “Directive (EU) 2019/882 of the European Parliament and of the Council of 17 April 2019 on the accessibility requirements for products and services”. We can see which services it applies to in chapter 1 article 2 section 2, where we see (f) e-commerce services. So that’s the first part.

But where do we find out what accessibility standards the EAA tells us we need to meet? That’s more of a journey. First we need to look at section 46, that says that the accessibility requirements of this Directive should be aligned to the requirements of Directive (EU) 2016/2102. What’s Directive (EU) 2016/2102? Turns out that it’s “Directive (EU) 2016/2102 of the European Parliament and of the Council of 26 October 2016 on the accessibility of the websites and mobile applications of public sector bodies”: the earlier public sector equivalent of the upcoming private sector European Accessibility Act. So far so good, let’s look at what that requires.

Looking at recital 37, we find a reference to a document called “European standard EN 301 549 V1.1.2”. We also see later, in recital 54, that the presumption is that the latest version of EN 301 549 is the most applicable.

EN 301 549 (latest version currently V3.2.1), also known as “Harmonised European Standard: Accessibility requirements for ICT products and services” is, then, the requirements document for the European Accessibility Act.

Finally, we want to know the website requirements. In EN 301 549 we find a whole bunch of clauses, but clause 9 dictates the requirements specific to web sites and web apps. While there is a little complexity here, we can effectively say that the requirement from clause 9 is for websites to reach WCAG 2.1 level-AA. For anyone who’s been working with accessibility for a little while this should feel both reasonable and obvious.

But why talk about dark mode?

So far we’ve looked at EN 301 549 clause 9: Web. But the harmonized standard is broad, and it turns out there are other requirements for web practitioners that aren’t just in section 9. For example, if we look at clause 10: Non-web Documents, you’ll find that documents linked from websites also need to be accessible. Hope that didn’t come as too big a shock. But we need to move on to clause 11: Software. At first glance it looks like we might be able to ignore this as not applicable to websites and web apps, but:

So from a website perspective we can ignore 11.1–11.5, but what’s left? 11.6 talks about platform requirements which we can also basically ignore, but 11.7 User Preferences is the crux of this blogpost, and it’s worth quoting in full:

Where software is not designed to be isolated from its platform, and provides a user interface, that user interface shall follow the values of the user preferences for platform settings for: units of measurement, colour, contrast, font type, font size, and focus cursor except where they are overridden by the user

Basically, anything a user could choose at a platform level that is made available through the user’s browser is in scope for us being required to support it.

OK, deep breath. So far this is all very vague, but for the sake of argument, if these apply to websites, what does it mean? Luckily for us Pär Lannerö has been investigating this on ETSI’s GitLab, and while the thread is extremely long and detailed at this point, we can jump to Pär’s dissection of what a requirement to support user preferences for colour might mean to discover (as we probably already knew) that a user can pick a dark or light theme in nearly all major platforms these days, and all web browsers expose this to the page through the prefers-color-scheme media query.

And that means that if your site is light by default you need to offer a dark mode, and if your site is dark by default you need to offer a light mode.

Legal opinion

Hopefully the trail I’ve written up so far indicates that a requirement for a dark mode on ecommerce sites falls out of the directive, but none of this means anything if regulators are just going to test for WCAG 2.1 level-AA compliance and leave it at that. Well, so far we’ve got at least two indications that this isn’t going to be the case.

First, and the strongest indicator, is with Sweden. In Sweden the ownership of the ecommerce part of the European Accessibility Act lies with Post- och Telestyrelsen (PTS), who are collaborating with the Agency for Digital Government (DIGG) to assess sites after the law comes into force in June. DIGG have put up a page (in Swedish) titled “Respect users’ settings” as part of their guidelines for web that specifically calls out dark mode as a requirement and links it through to EN 301 549 clause 11.7.

Another, although milder, indicator is from the German BIK BITV-Test, which is the test used by the German government to audit government websites. While not specifically calling out dark mode by name, they do show that as official[1] auditors they view clause 11.7 as required for websites and list other required colour options, such as support for forced colours.

Summing it up

I hope I’ve drawn a line between the and the requirement for a dark mode for ecommerce sites, but there are definitely tenuous links in the chain. My general feeling though is to pull back for a wider look at this. While I’ve focused on the legal compliance aspect in this post, making things that use the inherent benefits of digital interfaces to provide an experience that works for users regardless of their needs, opens up pathways to potential new customers that we couldn’t have reached before and makes the process easier and more satisfying for our existing ones.

  1. I thought that BIK BITV was official, but it turns out that that wasn’t correct. ⤴️