This is a great bit of detective work by Amber! It’s the puzzling case of The Browser Dev Tools and the Missing Computed Values from Custom Properties.
Who do I know working on dev tools for Chrome, Firefox, or Safari that can help Amber find an answer to this mystery?
I count at least three clever CSS techniques I didn’t know about.
Matthias has a good solution for dealing with the behaviour of CSS custom properties I wrote about: first set your custom properties with the fallback and then use feature queries (@supports) to override those values.
Yet another clever technique from Lea. But I’m also bookmarking this one because of something she points out about custom properties:
The browser doesn’t know if your property value is valid until the variable is resolved, and by then it has already processed the cascade and has thrown away any potential fallbacks.
That explains an issue I was seeing recently! I couldn’t understand why an older browser wasn’t getting the fallback I had declared earlier in the CSS. Turns out that custom properties mess with that expectation.
Sara shares how she programmes with custom properties in CSS. It sounds like her sensible approach aligns quite nicely with Andy’s CUBE CSS methodology.
Oh, and she’s using Fractal to organise her components:
I’ve been using Fractal for a couple of years now. I chose it over other pattern library tools because it fit my needs perfectly — I wanted a tool that was unopinionated and flexible enough to allow me to set up and structure my project the way I wanted to. Fractal fit the description perfectly because it is agnostic as to the way I develop or the tools I use.
I’m not the only one swapping out Sass with CSS for colour functions:
Because of the declarative nature of CSS, you’re never going to get something as terse as what you could get in Sass. So sure, you’re typing more characters. But you know what you’re not doing? Wrangling build plugins and updating dependencies to get Sass to build. What you write gets shipped directly to the browser and works as-is, now and for eternity. It’s hard to say that about your Sass code.
This is clever—using custom properties to enable if/else logic in CSS.
I don’t understand what currying is, but Trys points out a really interesting thing about custom properties in CSS:
The value after the : in the CSS custom property does not have to be valid CSS.
That means you can use custom properties to store arbitrary strings of text, which can then be combined within a calc() function, at which point they get evaluated.
Andy takes Utopia for a spin—it very much matches his approach.
This is the project that Trys and James have been working on at Clearleft. It’s a way of approaching modular scales in web typography that uses CSS locks and custom properties to fantastic effect.
Utopia is not a product, a plugin, or a framework. It’s a memorable/pretentious word we use to refer to a way of thinking about fluid responsive design.
It’s now easier than ever to style form controls without sacrificing semantics and accessibility:
The reason is that we can finally style the ::before and ::after pseudo-elements on the
<input>tag itself. This means we can keep and style an<input>and won’t need any extra elements. Before, we had to rely on the likes of an extra<div>or<span>, to pull off a custom design.
The demo is really nice. And best of all, you can wrap all of these CSS enhancements in a feaure query:
Hopefully, you’re seeing how nice it is to create custom form styles these days. It requires less markup, thanks to pseudo-elements that are directly on form inputs. It requires less fancy style switching, thanks to custom properties. And it has pretty darn good browser support, thanks to
@supports.
Lynn gives a step-by-step walkthrough of the latest amazing redesign of her website. There’s so much joy and craft in here, with real attention to detail—I love it!
If you ignore the slightly insulting and condescending clickbaity title, this is a handy run-down of eight browser features with good support:
addEventListener(),scrollTo(),setTimeout() and setInterval(),defaultChecked property for checkboxes,normalize() and wholeText for strings of text,insertAdjacentElement() and insertAdjacentText(),event.detail, andscrollHeight and scrollWidth.Heydon cracks me up—his Patterns Day is going to have you crying with laughter; guaranteed!
Here he is talking about custom properties in CSS as part of his Making Future Interfaces video series.
CSS grid and custom properties really are a match made in heaven.
Er …I think Heydon might’ve cracked it. And by “it”, I mean container queries.
This is some seriously clever thinking involving CSS custom properties, calc, and flexbox. The end result is a component that can respond to its container …and nary a media query in sight!
I think Cathy might’ve buried the lede:
The knock on effect of this was removing media queries. As I moved towards some of the more modern features of CSS the need to target specific screen sizes with unique code was removed.
But on the topic of Sass, layout is now taken care of with CSS grid, variables are taken care of with CSS custom properties, and mixins for typography are taken care of with calc().
Personally, I’ve always found the most useful feature of Sass to simply be that you can have lots of separate Sass files that get combined into one CSS file—very handy for component libraries.
I had to read through this twice, but I think I get it now (I’m not the sharpest knife in the drawer). Very useful if you’re doing theming in CSS.
In defence of the cascade (especially now that we’ve got CSS custom properties).
I think embracing CSS’s cascade can be a great way to encourage consistency and simplicity in UIs. Rather than every new component being a free for all, it trains both designers and developers to think in terms of aligning with and re-using what they already have.
Remember, every time you set a property in CSS you are in fact overriding something (even if it’s just the default user agent styles). In other words, CSS code is mostly expressing exceptions to a default design.
On Ev’s blog, Marcin goes into great detail on theming an interface using CSS custom properties, SVG, HSL, and a smattering of CSS filters.
I was kind of amazed that all of this could happen via CSS and CSS alone: the colours, the transitions, the vectors, and even the images.