Tags: mode



Wednesday, March 17th, 2021

Building Dark Mode | Product Blog • Sentry

Robin makes a good point here about using dark mode thinking as a way to uncover any assumptions you might have unwittingly baked into your design:

Given its recent popularity, you might believe dark mode is a fad. But from a design perspective, dark mode is exceptionally useful. That’s because a big part of design is about building relationships between colors. And so implementing dark mode essentially forced everyone on the team to think long, hard, and consistently about our front-end design components. In short, dark mode helped our design system not only look good, but make sense.

So even if you don’t actually implement dark mode, acting as though it’s there will give you a solid base to build in.

I did something similar with the back end of Huffduffer and The Session—from day one, I built them as though the interface would be available in multiple languages. I never implemented multi-language support, but just the awareness of it saved me from baking in any shortcuts or assumptions, and enforced a good model/view/controller separation.

For most front-end codebases, the design of your color system shows you where your radioactive styles are. It shows you how things are tied together, and what depends on what.

Tuesday, March 16th, 2021

Thursday, March 11th, 2021

When service workers met framesets

Oh boy, do I have some obscure browser behaviour for you!

To set the scene…

I’ve been writing here in my online journal for almost twenty years. The official anniversary will be on September 30th. But this website has been even online longer than that, just in a very different form.

Here’s the first version of adactio.com.

Like a tour guide taking you around the ruins of some lost ancient civilisation, let me point out some interesting features:

  • Observe the .shtml file extension. That means it was once using Apache’s server-side includes, a simple way of repeating chunks of markup across pages. Scientists have been trying to reproduce the wisdom of the ancients using modern technology ever since.
  • See how the layout is 100vw and 100vh? Well, this was long before viewport units existed. In fact there is no CSS at all on that page. It’s one big table element with 100% width and 100% height.
  • So if there’s no CSS, where is the border-radius coming from? Let me introduce you to an old friend—the non-animated GIF. It’s got just enough transparency (though not proper alpha transparency) to fake rounded corners between two solid colours.
  • The management takes no responsibility for any trauma that might befall you if you view source. There you will uncover JavaScript from the dawn of time; ancient runic writing like if (navigator.appName == "Netscape")

Now if your constitution was able to withstand that, brace yourself for what happens when you click on either of the two links, deutsch or english.

You find yourself inside a frameset. You may also experience some disorienting “DHTML”—the marketing term given to any combination of JavaScript and positioning in the late ’90s.

Note that these are not iframes, they are frames. Different thing. You could create single page apps long before Ajax was a twinkle in Jesse James Garrett’s eye.

If you view source, you’ll see a React-like component system. Each frameset component contains frame components that are isolated from one another. They’re like web components. Each frame has its own (non-shadow) DOM. That’s because each frame is actually a separate web page. If you right-click on any of the frames, your browser should give the option to view the framed document in its own tab or window.

Now for the part where modern and ancient technologies collide…

If you’re looking at the frameset URL in Firefox or Safari, everything displays as it should in all its ancient glory. But if you’re looking in Google Chrome and you’ve visited adactio.com before, something very odd happens.

Each frame of the frameset displays my custom offline page. The only way that could be served up is through my service worker script. You can verify this by opening the framest URL in an incognito window—everything works fine when no service worker has been registered.

I have no idea why this is happening. My service worker logic is saying “if there’s a request for a web page, try fetching it from the network, otherwise look in the cache, otherwise show an offline page.” But if those page requests are initiated by a frame element, it goes straight to showing the offline page.

Is this a bug? Or perhaps this is the correct behaviour for some security reason? I have no idea.

I wonder if anyone has ever come across this before. It’s a very strange combination of factors:

  • a domain served over HTTPS,
  • that registers a service worker,
  • but also uses framesets and frames.

I could submit a bug report about this but I fear I would be laughed out of the bug tracker.

Still …the World Wide Web is remarkable for its backward compatibility. This behaviour is unusual because browser makers are at pains to support existing content and never break the web.

Technically a modern website (one that registers a service worker) shouldn’t be using deprecated technology like frames. But browsers still need to be able support those old technologies in order to render old websites.

This situation has only arisen because the same domain—adactio.com—is host to a modern website and a really old one.

Maybe Chrome is behaving strangely because I’ve built my online home on ancient burial ground.

Update: Both Remy and Jake did some debugging and found the issue…

It’s all to do with navigation preloads and the value of event.preloadResponse, which I believe is only supported in Chrome which would explain the differences between browsers.

According to this post by Jake:

event.preloadResponse is a promise that resolves with a response, if:

  • Navigation preload is enabled.
  • The request is a GET request.
  • The request is a navigation request (which browsers generate when they’re loading pages, including iframes).

Otherwise event.preloadResponse is still there, but it resolves with undefined.

Notice that iframes are mentioned, but not frames.

My code was assuming that if event.preloadRepsonse exists in my block of code for responding to page requests, then there’d be a response. But if the request was initiated from a frameset, it is a request for a page and event.preloadRepsonse does exist …but it’s undefined.

I’ve updated my code now to check this assumption (and fall back to fetch).

This may technically still be a bug though. Shouldn’t a page loaded from a frameset count as a navigation request?

Tuesday, December 22nd, 2020

SVGs in dark mode

I added a dark mode to my site last year. Since then I’ve been idly toying with the addition of a dark mode to The Session too.

As with this site, the key to adding a dark mode was switching to custom properties for color and background-color declarations. But my plans kept getting derailed by the sheet music on the site. The sheet music is delivered as SVG generated by ABCJS which hard-codes the colour in stroke and fill attributes:

fill="#000000" stroke="#000000"

When I was describing CSS recently I mentioned the high specifity of inline styles:

Whereas external CSS and embedded CSS don’t have any effect on specificity, inline styles are positively radioactive with specificity.

Given that harsh fact of life, I figured it would be nigh-on impossible to over-ride the colour of the sheetmusic. But then I realised I was an idiot.

The stroke and fill attributes in SVG are presentational but they aren’t inline styles. They’re attributes. They have no affect on specifity. I can easily over-ride them in an external style sheet.

In fact, if I had actually remembered what I wrote when I was adding a dark mode to adactio.com, I could’ve saved myself some time:

I have SVGs of sparklines on my homepage. The SVG has a hard-coded colour value in the stroke attribute of the path element that draws the sparkline. Fortunately, this can be over-ridden in the style sheet:

svg.activity-sparkline path {
  stroke: var(--text-color);

I was able to do something similar on The Session. I used the handy currentColor keyword in CSS so that the sheet music matched the colour of the text:

svg path {
  fill: currentColor;
svg path:not(stroke="none") {
  stroke: currentColor;

Et voila! I now had light-on-dark sheet music for The Session’s dark mode all wrapped up in a prefers-color-scheme: dark media query.

I pushed out out the new feature and started getting feedback. It could be best summarised as “Thanks. I hate it.”

It turns out that while people were perfectly fine with a dark mode that inverts the colours of text, it felt really weird and icky to do the same with sheet music.

On the one hand, this seems odd. After all, sheet music is a writing system like any other. If you’re fine with light text on a dark background, why doesn’t that hold for light sheet music on a dark background?

But on the other hand, sheet music is also like an image. And we don’t invert the colours of our images when we add a dark mode to our CSS.

With that in mind, I went back to the drawing board and this time treated the sheet music SVGs as being intrinsicly dark-on-light, rather than a stylistic choice. It meant a few more CSS rules, but I’m happy with the final result. You can see it in action by visiting a tune page and toggling your device’s “appearance” settings between light and dark.

If you’re a member of The Session, I also added a toggle switch to your member profile so you can choose dark or light mode regardless of your device settings.

Thursday, October 1st, 2020

Exploring the future of… Design teams | Clearleft

I’ll be moderating this online panel next week with Emma Boulton, Holly Habstritt Gaal, Jean Laleuf, and Lola Oyelayo-Pearson.

There are still some spots available—it’s free to register. The discussion won’t be made public; the Chatham House Rule applies.

I’m looking forward to it! Come along if you’re interested in the future of design teams.

What will the near-future look like for design teams? Join us as we explore how processes, team structures and culture might change as our industry matures and grows.

Friday, July 3rd, 2020

Dark mode revisited

I added a dark mode to my website a while back. It was a fun thing to do during Indie Web Camp Amsterdam last year.

I tied the colour scheme to the operating system level. If you choose a dark mode in your OS, my website will adjust automatically thanks to the prefers-color-scheme: dark media query.

But I’ve seen notes from a few friends, not about my site specifically, but about how they like having an explicit toggle for dark mode (as well as the media query). Whenever I read those remarks, I’d think “I’m really not sure I’ve got time to deal with adding that kind of toggle to my site.”

But then I realised, “Jeremy, you absolute muffin! You’ve had a theme switcher on your website for almost two decades now!”

Doh! I had forgotten about that theme switcher. It dates back to the early days of CSS. I wanted my site to be a demonstration of how you could apply different styles to the same underlying markup (this was before the CSS Zen Garden came along). Those themes are very dated now, but if you like you can view my site with a Zeldman theme or a sci-fi theme.

To offer a dark-mode theme for my site, all I had to do was take the default stylesheet, pull out the custom properties from the prefers-color-scheme: dark media query, and done. It took less than five minutes.

So if you want to view my site in dark mode, it’s one of the options in the “Customise” dropdown on every page of the website.

Friday, June 12th, 2020

Saturday, April 25th, 2020

Dark mode and variable fonts | CSS-Tricks

This is such a clever use of variable fonts!

We can use a lighter font weight to make the text easier to read whenever dark mode is active.

Monday, April 20th, 2020

Better Form Inputs for Better Mobile User Experiences | CSS-Tricks

Here’s one simple, practical way to make apps perform better on mobile devices: always configure HTML input fields with the correct type, inputmode, and autocomplete attributes. While these three attributes are often discussed in isolation, they make the most sense in the context of mobile user experience when you think of them as a team.

This is an excellent deep dive with great advice:

You may think that you are familiar with the basic autocomplete options, such as those that help the user fill in credit card numbers or address form fields, but I’d urge you to review them to make sure that you are aware of all of the options. The spec lists over 50 values!

Thursday, March 26th, 2020

Let a website be a worry stone. — Ethan Marcotte

It was a few years before I realized that worry stones had a name, that they were borrowed from cultures other and older than mine. Heck, it’s been more than a few years since I’ve even held one. But in the last few weeks, before and after launching the redesign, I’ve kept working away at this website, much as I’d distractedly run my fingers over a smooth, flat stone.

Friday, February 28th, 2020

Why the GOV.UK Design System team changed the input type for numbers - Technology in government

Some solid research here. Turns out that using input type=”text” inputmode=”numeric” pattern="[0-9]*" is probably a better bet than using input type="number".

Tuesday, November 19th, 2019

Modest JS Works | You were never sold on heavy-handed JavaScript approaches. Here’s a case for keeping your JS modest.

The fat JavaScript stacks-du-jour have a lot of appeal. They promise you to be able to do more with less. But what if I want to do less?

This is a terrific little (free!) online book all about modest JavaScript. The second part has practical code, but it’s the first part—all about the principles of staying lean—that really resonates with me.

Don’t build more JS than you can maintain over the long term. If you’re going to be building something for a long time, make sure what you are building will grow with you. Make sure you don’t depend on other people’s work too much, lest you want to keep refactoring your code when the framework you picked goes out of style.

Monday, October 14th, 2019

The rise of research ops — a view from the inside | Clearleft

I moderated this panel in London last week, all about the growing field of research ops—I genuinely love moderating panels. Here, Richard recounts some of the thought nuggets I prised from the mind casings of the panelists.

Sunday, October 6th, 2019

Dark mode

I had a very productive time at Indie Web Camp Amsterdam. The format really lends itself to getting the most of a weekend—one day of discussions followed by one day of hands-on making and doing. You should definitely come along to Indie Web Camp Brighton on October 19th and 20th to experience it for yourself.

By the end of the “doing” day, I had something fun to demo—a dark mode for my website.

Y’know, when I first heard about Apple adding dark mode to their OS—and also to CSS—I thought, “Oh, great, Apple are making shit up again!” But then I realised that, like user style sheets, this is one more reminder to designers and developers that they don’t get the last word—users do.

Applying the dark mode styles is pretty straightforward in theory. You put the styles inside this media query:

@media (prefers-color-scheme: dark) {

Rather than over-riding every instance of a colour in my style sheet, I decided I’d do a little bit of refactoring first and switch to using CSS custom properties (or variables, if you will).

:root {
  --background-color: #fff;
  --text-color: #333;
  --link-color: #b52;
body {
  background-color: var(--background-color);
  color: var(--text-color);
a {
  color: var(--link-color);

Then I can over-ride the custom properties without having to touch the already-declared styles:

@media (prefers-color-scheme: dark) {
  :root {
    --background-color: #111416
    --text-color: #ccc;
    --link-color: #f96;

All in all, I have about a dozen custom properties for colours—variations for text, backgrounds, and interface elements like links and buttons.

By using custom properties and the prefers-color-scheme media query, I was 90% of the way there. But the devil is in the details.

I have SVGs of sparklines on my homepage. The SVG has a hard-coded colour value in the stroke attribute of the path element that draws the sparkline. Fortunately, this can be over-ridden in the style sheet:

svg.activity-sparkline path {
  stroke: var(--text-color);

The real challenge came with the images I use in the headers of my pages. They’re JPEGs with white corners on one side and white gradients on the other.

header images

I could make them PNGs to get transparency, but the file size would shoot up—they’re photographic images (with a little bit of scan-line treatment) so JPEGs (or WEBPs) are the better format. Then I realised I could use CSS to recreate the two effects:

  1. For the cut-out triangle in the top corner, there’s clip-path.
  2. For the gradient, there’s …gradients!
background-image: linear-gradient(
  to right,
  transparent 50%,
  var(—background-color) 100%

Oh, and I noticed that when I applied the clip-path for the corners, it had no effect in Safari. It turns out that after half a decade of support, it still only exists with -webkit prefix. That’s just ridiculous. At this point we should be burning vendor prefixes with fire. I can’t believe that Apple still ships standardised CSS properties that only work with a prefix.

In order to apply the CSS clip-path and gradient, I needed to save out the images again, this time without the effects baked in. I found the original Photoshop file I used to export the images. But I don’t have a copy of Photoshop any more. I haven’t had a copy of Photoshop since Adobe switched to their Mafia model of pricing. A quick bit of searching turned up Photopea, which is pretty much an entire recreation of Photoshop in the browser. I was able to open my old PSD file and re-export my images.

LEGO clone trooper Brighton bandstand Scaffolding Tokyo Florence

Let’s just take a moment here to pause and reflect on the fact that we can now use CSS to create all sorts of effects that previously required a graphic design tool like Photoshop. I could probably do those raster scan lines with CSS if I were smart enough.

dark mode

This is what I demo’d at the end of Indie Web Camp Amsterdam, and I was pleased with the results. But fate had an extra bit of good timing in store for me.

The very next day at the View Source conference, Melanie Richards gave a fantastic talk called The Tailored Web: Effectively Honoring Visual Preferences (seriously, conference organisers, you want this talk on your line-up). It was packed with great insights and advice on impementing dark mode, like this little gem for adjusting images:

@media (prefers-color-scheme: dark) {
  img {
    filter: brightness(.8) contrast(1.2);

Melanie also pointed out that you can indicate the presence of dark mode styles to browsers, although the mechanism is yet to shake out. You can do it in CSS:

:root {
  color-scheme: light dark;

But you can also do it in HTML:

That allows browsers to swap out replaced content; interface elements like form fields and dropdowns.

Oh, and one other addition I added after the fact was swapping out map imagery by using the picture element to point to darker map tiles:

<source media="(prefers-color-scheme: dark)" srcset="https://api.mapbox.com/styles/v1/mapbox/dark-v10/static...">
<img src="https://api.mapbox.com/styles/v1/mapbox/outdoors-v10/static..." alt="map">

light map dark map

So now I’ve got a dark mode for my website. Admittedly, it’s for just one of the eight style sheets. I’ve decided that, while I’ll update my default styles at every opportunity, I’m going to preservethe other skins as they are, like the historical museum pieces they are.

If you’re on the latest version of iOS, go ahead and toggle the light and dark options in your system preferences to flip between this site’s colour schemes.

Friday, August 9th, 2019

Meaning without markup: Accessibility Object Model

Hidde gives an in-depth explanation of the Accessibility Object Model, coming soon to browsers near you:

In a way, that’s a bit like what Service Workers do for the network and Houdini for style: give developers control over something that was previously done only by the browser.

Wednesday, May 29th, 2019

Friday, May 24th, 2019

Night Mode with Mix Blend Mode: Difference

Here’s a clever shortcut to creating a dark mode by using mix-blend-mode: difference.

Friday, March 29th, 2019

CERN Hack days – Chiteri’s Blog

Martin gives a personal history of his time at the two CERN hack projects …and also provides a short history of the universe.

Sunday, January 13th, 2019

Teaching a Correct CSS Mental Model

One facet of this whole CSS debate involves one side saying, “Just learn CSS” and the other side responding, “That’s what I’ve been trying to do!”

I think it’s high time we the teachers of CSS start discussing how exactly we can teach a correct mental model. How do we, in specific and practical ways, help developers get past this point of frustration. Because we have not figured out how to properly teach a mental model of CSS.