Journal tags: colour



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.

Programming CSS to perform Sass colour functions

I wrote recently about moving away from Sass to using native CSS features. I had this to say on the topic of mixins in Sass:

These can be very useful, but now there’s a lot that you can do just in CSS with calc(). The built-in darken() and lighten() mixins are handy though when it comes to colours.

I know we will be getting these in the future but we’re not there yet with CSS.

Anyway, I had all this in the back of my mind when I was reading Lea’s excellent feature in this month’s Increment: A user’s guide to CSS variables. She’s written about a really clever technique of combining custom properites with hsl() colour values for creating colour palettes. (See also: Una’s post on dynamic colour theming with pure CSS.)

As so often happens when I’m reading something written by Lea—or seeing her give a talk—light bulbs started popping over my head (my usual response to Lea’s knowledge bombs is either “I didn’t know you could do that!” or “I never thought of doing that!”).

I immediately set about implementing this technique over on The Session. The trick here is to use separate custom properties for the hue, saturation, and lightness parts of hsl() colour values. Then, when you want to lighten or darken the colour—say, on hover—you can update the lightness part.

I’ve made a Codepen to show what I’m doing.

Let’s say I’m styling a button element. I make custom propertes for hsl() values:

button {
  --button-colour-hue: 19;
  --button-colour-saturation: 82%;
  --button-colour-lightness: 38%;
  background-color: hsl(

For my buttons, I want the borders to be slightly darker than the background colour. When I was using Sass, I used the darken() function to this. Now I use calc(). Here’s how I make the borders 10% darker:

border-color: hsl(
  calc(var(--button-colour-lightness) - 10%)

That calc() function is substracting a percentage from a percentage: 38% minus 10% in this case. The borders will have a lightness of 28%.

I make the bottom border even darker and the top border lighter to give a feeling of depth.

On The Session there’s a “cancel” button style that’s deep red.

Here’s how I set its colour:

.cancel {
  --button-colour-hue: 0;
  --button-colour-saturation: 100%;
  --button-colour-lightness: 40%;

That’s it. The existing button declarations take care of assigning the right shades for the border colours.

Here’s another example. Site admins see buttons for some actions only available to them. I want those buttons to have their own colour:

.admin {
  --button-colour-hue: 45;
  --button-colour-saturation: 100%;
  --button-colour-lightness: 40%;

You get the idea. It doesn’t matter how many differently-coloured buttons I create, the effect of darkening or lightening their borders is all taken care of.

So it turns out that the lighten() and darken() functions from Sass are available to us in CSS by using a combination of custom properties, hsl(), and calc().

I’m also using this combination to lighten or darken background and border colours on :hover. You can poke around the Codepen if you want to see that in action.

I love seeing the combinatorial power of these different bits of CSS coming together. It really is a remarkably powerful programming language.

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="">
<img src="" 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.

Designing the Patterns Day site

Patterns Day is not one of Clearleft’s slick’n’smooth conferences like dConstruct or UX London. It’s more of a spit’n’sawdust affair, like Responsive Day Out.

You can probably tell from looking at the Patterns Day website that it wasn’t made by a crack team of designers and developers—it’s something I threw together over the course of a few days. I had a lot of fun doing it.

I like designing in the browser. That’s how I ended up designing Resilient Web Design, The Session, and Huffduffer back in the day. But there’s always the initial problem of the blank page. I mean, I had content to work with (the information about the event), but I had no design direction.

My designery colleagues at Clearleft were all busy on client projects so I couldn’t ask any of them to design a website, but I thought perhaps they’d enjoy a little time-limited side exercise in producing ideas for a design direction. Initially I was thinking they could all get together for a couple of hours, lock themselves in a room, and bash out some ideas as though it were a mini hack farm. Coordinating calendars proved too tricky for that. So Jon came up with an alternative: a baton relay.

Remember Layer Tennis? I once did the commentary for a Layer Tennis match and it was a riot—simultaneously terrifying and rewarding.

Anyway, Jon suggested something kind of like that, but instead of a file being batted back and forth between two designers, the file would passed along from designer to designer. Each designer gets one art board in a Sketch file. You get to see what the previous designers have done, leaving you to either riff on that or strike off in a new direction.

The only material I supplied was an early draft of text for the website, some photos of the first confirmed speakers, and some photos I took of repeating tiles when I was in Porto (patterns, see?). I made it clear that I wasn’t looking for pages or layouts—I was interested in colour, typography, texture and “feel.” Style tiles, yes; comps, no.


Jon’s art board.

Jon kicks things off and immediately sets the tone with bright, vibrant colours. You can already see some elements that made it into the final site like the tiling background image of shapes, and the green-bordered text block. There are some interesting logo ideas in there too, some of them riffing on LEGO, others riffing on illustrations from Christopher Alexander’s book, A Pattern Language. Then there’s the typeface: Avenir Next. I like it.

James G

James G’s art board.

Jimmy G is up next. He concentrates on the tiles idea. You can see some of the original photos from Porto in the art board, alongside his abstracted versions. I think they look great, and I tried really hard to incorporate them into the site, but I couldn’t quite get them to sit with the other design elements. Looking at them now, I still want to get them into the site …maybe I’ll tinker with the speaker portraits to get something more like what James shows here.


Ed’s art board.

Ed picks up the baton and immediately iterates through a bunch of logo ideas. There’s something about the overlapping text that I like, but I’m not sure it fits for this particular site. I really like the effect of the multiple borders though. With a bit more time, I’d like to work this into the site.

James B

Batesy’s art board.

Batesy is the final participant. He has some other nice ideas in there, like the really subtle tiling background that also made its way into the final site (but I’ll pass on the completely illegible text on the block of bright green). James works through two very different ideas for the logo. One of them feels a bit too busy and chaotic for me, but the other one …I like it a lot.

I immediately start thinking “Hmm …how could I make this work in a responsive way?” This is exactly the impetus I needed. At this point I start diving into CSS. Not only did I have some design direction, I’m champing at the bit to play with some of these ideas. The exercise was a success!

Feel free to poke around the Patterns Day site. And while you’re there, pick up a ticket for the event too.