Tags: colour

It’s often said that it’s easier to make a fast website than it is to keep a website fast. Things slip through. If you’re not vigilant, performance can erode without you noticing.

It’s a similar story for other invisible but important facets of your website: privacy, security, accessibility. Because they’re hidden from view, you won’t be able to see if there’s a regression.

That’s why it’s a good idea to have regular audits for performance, privacy, security, and accessibility.

I wrote about accessibility testing a while back, and how there’s quite a bit that you can do for yourself before calling in an expert to look at the really gnarly stuff:

When you commission an accessibility audit, you want to make sure you’re getting the most out of it. Don’t squander it on issues that you can catch and fix yourself. Make sure that the bulk of the audit is being spent on the specific issues that are unique to your site.

I recently did an internal audit of the Clearleft website. After writing up the report, I also did a lunch’n’learn to share my methodology. I wanted to show that there’s some low-hanging fruit that pretty much anyone can catch.

To start with, there’s keyboard navigation. Put your mouse and trackpad to one side and use the tab key to navigate around.

Caveat: depending on what browser you’re using, you might need to update some preferences for keyboard navigation to work on links. If you’re using Safari, go to “Preferences”, then “Advanced”, and tick “Press Tab to highlight each item on a web page.”

Tab around and find out. You should see some nice chunky :focus-visible styles on links and form fields.

Here’s something else that anyone can do: zoom in. Increase the magnification to 200%. Everything should scale proportionally. How about 500%? You’ll probably see a mobile-friendly layout. That’s fine. As long as nothing is broken or overlapping, you’re good.

At this point, I reach for some tools. I’ve got some bookmarklets that do similar things: tota11y and ANDI. They both examine the source HTML and CSS to generate reports on structure, headings, images, forms, and so on.

These tools are really useful, but you need to be able to interpret the results. For example, a tool can tell you if an image has no alt text. But it can’t tell you if an image has good or bad alt text.

Likewise, these tools are great for catching colour-contrast issues. But there’s a big difference between a colour-contrast issue on the body copy compared to a colour-contrast issue on one unimportant page element.

I think that demonstrates the most important aspect of any audit: prioritisation.

Finding out that you have accessibility issues isn’t that useful if they’re all presented as an undifferentiated list. What you really need to know are which issues are the most important to fix.

By the way, I really like the way that the Gov.uk team prioritises accessibility concerns:

The team puts accessibility concerns in 2 categories:

1. Theoretical: A question or statement regarding the accessibility of an implementation within the Design System without evidence of real-world impact.
2. Evidenced: Sharing new research, data or evidence showing that an implementation within the Design System could cause barriers for disabled people.

The team will usually prioritise evidenced issues and queries over theoretical ones.

When I wrote up my audit for the Clearleft website, I structured it in order of priority. The most important things to fix are at the start of the audit. I also used a simple scale for classifying the severity of issues: low, medium, and high priority.

Thankfully there were no high-priority issues. There were a couple of medium-priority issues. There were plenty of low-priority issues. That’s okay. That’s a pretty good distribution.

If you’re interested, here’s the report I delivered…

Accessibility audit on clearleft.com

Colour contrast

There are a few issues with the pink colour. When it’s used on a grey background, or when it’s used as a background colour for white text, the colour contrast isn’t high enough.

The SVG arrow icon could be improved too.

Recommendations

Medium priority

• Change the pink colour universally to be darker. The custom property --red is currently rgb(234, 33, 90). Change it to rgb(210, 20, 73) (thanks, James!)

Low priority

• The SVG arrow icon currently uses currentColor. Consider hardcoding solid black (or a very, very dark grey) instead.

Images

Alt text is improving on the site. There’s reasonable alt text at the top level pages and the first screen’s worth of case studies and blog posts. I made a sweep through these pages a while back to improve the alt text but I haven’t done older blog posts and case studies.

Recommendations

Medium priority

• Make a sweep of older blog posts and case studies and fix alt text.

Low priority

• Images on the contact page have alt text that starts with “A photo of…” — this is redundant and can be removed.

Headings

The site is using headings sensibly. Sometimes the nesting of headings isn’t perfect, but this is a low priority issue. For example, on the contact page there’s an h1 followed by two h3s. In theory this isn’t correct. In practice (for screen reader users) it’s not an issue.

Recommendations

Low priority

• On the home page, “UX London 2023” should probably be h3 instead of h1.
• On the case studies index page we’re currently using h3 headings for the industry sector (“Charities”, “Education” etc.) but these should probably not be headings at all. On the blog index page we use a class “Tags” for a similar purpose. Consider reusing that pattern on the case studies index page.
• On the about index page, “We’re driven to be” is an h3 and the subsequent three headings are h2s. Ideally this would be reversed: a single h2 followed by three h3s.

Link text

Sometimes the same text is used for different links.

Recommendations

Low priority

• On the home page the text “Read the case study” is re-used for multiple links. It would be better if each link were different e.g. “Read about The Natural History Museum.”

Forms

The only form on the site is the newsletter sign-up form. It’s marked up pretty well: the input has an associated label, although a visible (clickable) label would be better.

Tabbing order

The site doesn’t use JavaScript to mess with tabbing order for keyboard users. The source order of elements in the markup generally makes sense so all is good.

The focus styles are nice and clear too!

Structure

The site is using HTML landmark elements sensibly (header, nav, main, footer, etc.).

While I’m talking about the SVGs on The Session, I thought I’d share something else related to the rendering of the sheet music.

Like I said, I use the brilliant abcjs JavaScript library. It converts ABC notation into sheet music on the fly, which still blows my mind.

If you view source on the rendered SVG, you’ll see that the path and rect elements have been hard-coded with a colour value of #000000. That makes sense. You’d want to display sheet music on a light background, probably white. So it seems like a safe assumption.

Ah, but when it comes to front-end development, assumptions are like little hidden bombs just waiting to go off!

I got an email the other day:

Hi Jeremy,

I have vision problems, so I need to use high-contrast mode (using Windows 11). In high-contrast mode, the sheet-music view is just black!

Doh! All my CSS adapts just fine to high-contrast mode, but those hardcoded hex values in the SVG aren’t going to be affected by high-contrtast mode.

Stepping back, the underlying problem was that I didn’t have a full separation of concerns. Most of my styling information was in my CSS, but not all. Those hex values in the SVG should really be encoded in my style sheet.

I couldn’t remove the hardcoded hex values—not without messing around with JavaScript beyond my comprehension—so I made the fix in CSS:

[fill="#000000"] {
  fill: currentColor;
}
[stroke="#000000"] {
  stroke: currentColor;
}

That seemed to do the trick. I wrote back to the person who had emailed me, and they were pleased as punch:

Well done, Thanks!  The staff, dots, etc. all appear as white on a black background.  When I click “Print”, it looks like it still comes out black on a white background, as expected.

I’m very grateful that they brought the issue to my attention. If they hadn’t, that assumption would still be lying in wait, preparing to ambush someone else.

I was doing some accessibility work with a client a little while back. It was mostly giving their site the once-over, highlighting any issues that we could then discuss. It was an audit of sorts.

While I was doing this I started to realise that not all accessibility issues are created equal. I don’t just mean in their severity. I mean that some issues can—and should—be caught early on, while other issues can only be found later.

Take colour contrast. This is something that should be checked before a line of code is written. When designs are being sketched out and then refined in a graphical editor like Figma, that’s the time to check the ratio between background and foreground colours to make sure there’s enough contrast between them. You can catch this kind of thing later on, but by then it’s likely to come with a higher cost—you might have to literally go back to the drawing board. It’s better to find the issue when you’re at the drawing board the first time.

Then there’s the HTML. Most accessibility issues here can be caught before the site goes live. Usually they’re issues of ommission: form fields that don’t have an explicitly associated label element (using the for and id attributes); images that don’t have alt text; pages that don’t have sensible heading levels or landmark regions like main and nav. None of these are particularly onerous to fix and they come with the biggest bang for your buck. If you’ve got sensible forms, sensible headings, alt text on images, and a solid document structure, you’ve already covered the vast majority of accessibility issues with very little overhead. Some of these checks can also be automated: alt text for images; labels for inputs.

Then there’s interactive stuff. If you only use native HTML elements you’re probably in the clear, but chances are you’ve got some bespoke interactivity on your site: a carousel; a mega dropdown for navigation; a tabbed interface. HTML doesn’t give you any of those out of the box so you’d need to make your own using a combination of HTML, CSS, JavaScript and ARIA. There’s plenty of testing you can do before launching—I always ask myself “What would Heydon do?”—but these components really benefit from being tested by real screen reader users.

So if you commission an accessibility audit, you should hope to get feedback that’s mostly in that third category—interactive widgets.

If you get feedback on document structure and other semantic issues with the HTML, you should fix those issues, sure, but you should also see what you can do to stop those issues going live again in the future. Perhaps you can add some steps in the build process. Or maybe it’s more about making sure the devs are aware of these low-hanging fruit. Or perhaps there’s a framework or content management system that’s stopping you from improving your HTML. Then you need to execute a plan for ditching that software.

If you get feedback about colour contrast issues, just fixing the immediate problem isn’t going to address the underlying issue. There’s a process problem, or perhaps a communication issue. In that case, don’t look for a technical solution. A design system, for example, will not magically fix a workflow issue or route around the problem of designers and developers not talking to each other.

When you commission an accessibility audit, you want to make sure you’re getting the most out of it. Don’t squander it on issues that you can catch and fix yourself. Make sure that the bulk of the audit is being spent on the specific issues that are unique to your site.

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.