Tags: color

Whenever a new version of Chrome comes out, there’s an accompanying blog post listing what’s new. Chrome 93 just came out and, sure enough, Pete has written a blog post about it.

But what I think is the most exciting addition to the browser isn’t listed.

What is this feature that’s got me so excited?

Okay, I’ve probably oversold it now because actually, it looks like a rather small trivial addition. It’s the accent-color property in CSS.

Up until now, accent colour was controlled by the operating system. If you’re on a Mac, go to “System Preferences” and then “General”. There you’ll see an option to change your accent colour. Try picking a different colour. You’ll see that change cascade down into the other form fields in that preference pane: checkboxes, radio buttons, and dropdowns.

Your choice will also cascade down into web pages. Any web page that uses native checkboxes, radio buttons and other interface elements will inherit that colour.

This is how interface elements are supposed to work. The browser inherits the look’n’feel of the inputs from the operating system.

That’s the theory anyway. In practice, form elements—such as dropdowns—can look different from browser to browser, something that shouldn’t be happening if the browsers are all inheriting from the operating system.

Anyway, it’s probably this supposed separation of responsibility between browser and operating system which has led to the current situation with form fields and CSS. Authors can style form fields up to a point, but there’s always a line that you don’t get to cross.

The accent colour of a selected radio button or a checkbox has historically been on the other side of that line. You either had to accept that you couldn’t change the colour, or you had to make your own checkbox or radio button interface. You could use CSS to hide the native element and replace it with an image instead.

That feels a bit over-engineered and frankly kind of hacky. It reminds me of the bad old days of image replacement for text before we had web fonts.

Now, with the accent-color property in CSS, authors can over-ride the choice that the user has set at the operating system level.

On the one hand, this doesn’t feel great to me. Who are we to make that decision? Shouldn’t the user’s choice take primacy over our choices?

But then again, where do we draw the line? We’re allowed over-ride link colours. We’re allowed over-ride font choices.

Ultimately I think it’s a good thing that authors can now specify an accent colour. What makes me think that is the behaviour that authors have shown if they don’t have this ability—they do it anyway, and in a hackier manner. This is why I think the work of the Open UI group is so important. If developers don’t get a standardised way to customise native form controls, they’ll just recreate their own over-engineered versions.

The purpose of Open UI to the web platform is to allow web developers to style and extend built-in web UI controls, such as select dropdowns, checkboxes, radio buttons, and date/color pickers.

Trying to stop developers from styling checkboxes and radio buttons is like trying to stop teenagers from having sex. You might as well accept that it’s going to happen and give them contraception so they can at least do it safely.

So I welcome this new CSS condom.

You can see accent-color in action in this demo. Change the value of the accent-color property to see the form fields update:

:root {
  accent-color: rebeccapurple;
}

Applying it at the document level like that will make it universal, but you can also use the property on an element-by-element basis using whatever selector you want.

That demo works in Chrome and Edge 93, the current release. It also works in Firefox 92, which literally just landed (like as I was writing this blog post, support for accent-color magically arrived!).

As for Safari, well, who knows? If Apple published a roadmap, then developers would have a clue when to expect a property like this to land. But we mere mortals cannot be trusted with such important hush-hush information.

In the meantime, keep an eye on Can I Use. And lack of support on one browser is no reason not to use accent-color anyway. It’s a progressive enhancement. Add it to your CSS today and it will work in more browsers in the future.

If you download Safari Technology Preview you can test drive features that are on their way in Safari 15. One of those features, announced at Apple’s World Wide Developer Conference, is coloured browser chrome via support for the meta value of “theme-color.” Chrome on Android has supported this for a while but I believe Safari is the first desktop browser to add support. They’ve also added support for the media attribute on that meta element to handle “prefers-color-scheme.”

This is all very welcome, although it does remind me a bit of when Internet Explorer came out with the ability to make coloured scrollbars. I mean, they’re nice features’n’all, but maybe not the most pressing? Safari is still refusing to acknowledge progressive web apps.

That’s not quite true. In her WWDC video Jen demonstrates how you can add a progressive web app like Resilient Web Design to your home screen. I’m chuffed that my little web book made an appearance, but when you see how you add a site to your home screen in iOS, it’s somewhat depressing.

The steps to add a website to your home screen are:

1. Tap the “share” icon. It’s not labelled “share.” It’s a square with an arrow coming out of the top of it.
2. A drawer pops up. The option to “add to home screen” is nowhere to be seen. You have to pull the drawer up further to see the hidden options.
3. Now you must find “add to home screen” in the list

• Copy
• Add to Reading List
• Add Bookmark
• Add to Favourites
• Find on Page
• Add to Home Screen
• Markup
• Print

It reminds of this exchange in The Hitchhiker’s Guide To The Galaxy:

“You hadn’t exactly gone out of your way to call attention to them had you? I mean like actually telling anyone or anything.”

“But the plans were on display…”

“On display? I eventually had to go down to the cellar to find them.”

“That’s the display department.”

“With a torch.”

“Ah, well the lights had probably gone.”

“So had the stairs.”

“But look you found the notice didn’t you?”

“Yes,” said Arthur, “yes I did. It was on display in the bottom of a locked filing cabinet stuck in a disused lavatory with a sign on the door saying ‘Beware of The Leopard.’”

Safari’s current “support” for adding progressive web apps to the home screen feels like the minimum possible …just enough to use it as a legal argument if you happen to be litigated against for having a monopoly on app distribution. “Hey, you can always make a web app!” It’s true in theory. In practice it’s …suboptimal, to put it mildly.

Still, those coloured tab bars are very nice.

It’s a little bit weird that this stylistic information is handled by HTML rather than CSS. It’s similar to the meta viewport value in that sense. I always that the plan was to migrate that to CSS at some point, but here we are a decade later and it’s still very much part of our boilerplate markup.

Some people have remarked that the coloured browser chrome can make the URL bar look like part of the site so people might expect it to operate like a site-specific search.

I also wonder if it might blur “the line of death”; that point in the UI where the browser chrome ends and the website begins. Does the unified colour make it easier to spoof browser UI?

Probably not. You can already kind of spoof browser UI by using the right shade of grey. Although the removal any kind of actual line in Safari does give me pause for thought.

I tend not to think of security implications like this by default. My first thought tends to be more about how I can use the feature. It’s only after a while that I think about how bad actors might abuse the same feature. I should probably try to narrow the gap between those thoughts.