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Friday, July 24th, 2020

Custom Property Coverup | Amber’s Website

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?

Tuesday, July 7th, 2020

Custom properties

I made the website for the Clearleft podcast last week. The design is mostly lifted straight from the rest of the Clearleft website. The main difference is the masthead. If the browser window is wide enough, there’s a background image on the right hand side.

I mostly added that because I felt like the design was a bit imbalanced without something there. On the home page, it’s a picture of me. Kind of cheesy. But the image can be swapped out. On other pages, there are different photos. All it takes is a different class name on that masthead.

I thought about having the image be completely random (and I still might end up doing this). I’d need to use a bit of JavaScript to choose a class name at random from a list of possible values. Something like this:

var names = ['jeremy','katie','rich','helen','trys','chris'];
var name = names[Math.floor(Math.random() * names.length)];
document.querySelector('.masthead').classList.add(name);

(You could paste that into the dev tools console to see it in action on the podcast site.)

Then I read something completely unrelated. Cassie wrote a fantastic article on her site called Making lil’ me - part 1. In it, she describes how she made the mouse-triggered animation of her avatar in the footer of her home page.

It’s such a well-written technical article. She explains the logic of what she’s doing, and translates that logic into code. Then, after walking you through the native code, she shows how you could use the Greeksock library to achieve the same effect. That’s the way to do it! Instead of saying, “Here’s a library that will save you time—don’t worry about how it works!”, she’s saying “Here’s it works without a library; here’s how it works with a library; now you can make an informed choice about what to use.” It’s a very empowering approach.

Anyway, in the article, Cassie demonstrates how you can use custom properties as a bridge between JavaScript and CSS. JavaScript reads the mouse position and updates some custom properties accordingly. Those same custom properties are used in CSS for positioning. Voila! Now you’ve got the position of an element responding to mouse movements.

That’s what made me think of the code snippet I wrote above to update a class name from JavaScript. I automatically thought of updating a class name because, frankly, that’s how I’ve always done it. I’d say about 90% of the DOM scripting I’ve ever done involves toggling the presence of class values: accordions, fly-out menus, tool-tips, and other progressive disclosure patterns.

That’s fine. But really, I should try to avoid touching the DOM at all. It can have performance implications, possibly triggering unnecessary repaints and reflows.

Now with custom properties, there’s a direct line of communication between JavaScript and CSS. No need to use the HTML as a courier.

This made me realise that I need to be aware of automatically reaching for a solution just because that’s the way I’ve done something in the past. I should step back and think about the more efficient solutions that are possible now.

It also made me realise that “CSS variables” is a very limiting way of thinking about custom properties. The fact that they can be updated in real time—in CSS or JavaScript—makes them much more powerful than, say, Sass variables (which are more like constants).

But I too have been guilty of underselling them. I almost always refer to them as “CSS custom properties” …but a lot of their potential comes from the fact that they’re not confined to CSS. From now on, I’m going to try calling them custom properties, without any qualification.

Friday, July 3rd, 2020

Uncommon CSS Properties

I count at least three clever CSS techniques I didn’t know about.

Saturday, June 13th, 2020

CSS Custom Properties Fail Without Fallback · Matthias Ott – User Experience Designer

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.

Thursday, June 11th, 2020

CSS custom properties and the cascade

When I wrote about programming CSS to perform Sass colour functions I said this about the brilliant Lea Verou:

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!”).

Well, it happened again. This time I was reading her post about hybrid positioning with CSS variables and max() . But the main topic of the post wasn’t the part that made go “Huh! I never knew that!”. Towards the end of her article she explained something about the way that browsers evaluate CSS 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.

I’m used to being able to rely on the cascade. Let’s say I’m going to set a background colour on paragraphs:

p {
  background-color: red;
  background-color: color(display-p3 1 0 0);
}

First I’ve set a background colour using a good ol’ fashioned keyword, supported in browsers since day one. Then I declare the background colour using the new-fangled color() function which is supported in very few browsers. That’s okay though. I can confidently rely on the cascade to fall back to the earlier declaration. Paragraphs will still have a red background colour.

But if I store the background colour in a custom property, I can no longer rely on the cascade.

:root {
  --myvariable: color(display-p3 1 0 0);
}
p {
  background-color: red;
  background-color: var(--myvariable);
}

All I’ve done is swapped out the hard-coded color() value for a custom property but now the browser behaves differently. Instead of getting a red background colour, I get the browser default value. As Lea explains:

…it will make the property invalid at computed value time.

The spec says:

When this happens, the computed value of the property is either the property’s inherited value or its initial value depending on whether the property is inherited or not, respectively, as if the property’s value had been specified as the unset keyword.

So if a browser doesn’t understand the color() function, it’s as if I’ve said:

background-color: unset;

This took me by surprise. I’m so used to being able to rely on the cascade in CSS—it’s one of the most powerful and most useful features in this programming language. Could it be, I wondered, that the powers-that-be have violated the principle of least surprise in specifying this behaviour?

But a note in the spec explains further:

Note: The invalid at computed-value time concept exists because variables can’t “fail early” like other syntax errors can, so by the time the user agent realizes a property value is invalid, it’s already thrown away the other cascaded values.

Ah, right! So first of all browsers figure out the cascade and then they evaluate custom properties. If a custom property evaluates to gobbledygook, it’s too late to figure out what the cascade would’ve fallen back to.

Thinking about it, this makes total sense. Remember that CSS custom properties aren’t like Sass variables. They aren’t evaluated once and then set in stone. They’re more like let than const. They can be updated in real time. You can update them from JavaScript too. It’s entirely possible to update CSS custom properties rapidly in response to events like, say, the user scrolling or moving their mouse. If the browser had to recalculate the cascade every time a custom property didn’t evaluate correctly, I imagine it would be an enormous performance bottleneck.

So even though this behaviour surprised me at first, it makes sense on reflection.

I’ve probably done a terrible job explaining the behaviour here, so I’ve made a Codepen. Although that may also do an equally terrible job.

(Thanks to Amber for talking through this with me and encouraging me to blog about it. And thanks to Lea for expanding my mind. Again.)

Saturday, June 6th, 2020

Hybrid positioning with CSS variables and max() – Lea Verou

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.

Monday, June 1st, 2020

Global and Component Style Settings with CSS Variables — Sara Soueidan

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.

Sass Color Functions in CSS | Jim Nielsen’s Weblog

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.

Saturday, May 30th, 2020

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(
    var(--button-colour-hue),
    var(--button-colour-saturation),
    var(--button-colour-lightness)
  );
}

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(
  var(--button-colour-hue),
  var(--button-colour-saturation),
  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.

Global CSS options with custom properties | @mdo

This is clever—using custom properties to enable if/else logic in CSS.

Friday, February 28th, 2020

Currying in CSS? | Trys Mudford

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.

Tuesday, February 18th, 2020

Utopia

Trys and James recently unveiled their Utopia project. They’ve been tinkering away at it behind the scenes for quite a while now.

You can check out the website and read the blog to get the details of how it accomplishes its goal:

Elegantly scale type and space without breakpoints.

I may well be biased, but I really like this project. I’ve been asking myself why I find it so appealing. Here are a few of the attributes of Utopia that strike a chord with me…

It’s collaborative

Collaboration is at the heart of Clearleft’s work. I know everyone says that, but we’ve definitely seen a direct correlation: projects with high levels of collaboration are invariably more successful than projects where people are siloed.

The genesis for Utopia came about after Trys and James worked together on a few different projects. It’s all too easy to let design and development splinter off into their own caves, but on these projects, Trys and James were working (literally) side by side. This meant that they could easily articulate frustrations to one another, and more important, they could easily share their excitement.

The end result of their collaboration is some very clever code. There’s an irony here. This code could be used to discourage collaboration! After all, why would designers and developers sit down together if they can just pass these numbers back and forth?

But I don’t think that Utopia will appeal to designers and developers who work in that way. Born in the spirit of collaboration, I suspect that it will mostly benefit people who value collaboration.

It’s intrinsic

If you’re a control freak, you may not like Utopia. The idea is that you specify the boundaries of what you’re trying to accomplish—minimum/maximum font sizes, minumum/maximum screen sizes, and some modular scales. Then you let the code—and the browser—do all the work.

On the one hand, this feels like surrending control. But on the other hand, because the underlying system is so robust, it’s a way of guaranteeing quality, even in situations you haven’t accounted for.

If someone asks you, “What size will the body copy be when the viewport is 850 pixels wide?”, your answer would have to be “I don’t know …but I do know that it will be appropriate.”

This feels like a very declarative way of designing. It reminds me of the ethos behind Andy and Heydon’s site, Every Layout. They call it algorithmic layout design:

Employing algorithmic layout design means doing away with @media breakpoints, “magic numbers”, and other hacks, to create context-independent layout components. Your future design systems will be more consistent, terser in code, and more malleable in the hands of your users and their devices.

See how breakpoints are mentioned as being a very top-down approach to layout? Remember the tagline for Utopia, which aims for fluid responsive design?

Elegantly scale type and space without breakpoints.

Unsurprisingly, Andy really likes Utopia:

As the co-author of Every Layout, my head nearly fell off from all of the nodding when reading this because this is the exact sort of approach that we preach: setting some rules and letting the browser do the rest.

Heydon describes this mindset as automating intent. I really like that. I think that’s what Utopia does too.

As Heydon said at Patterns Day:

Be your browser’s mentor, not its micromanager.

The idea is that you give it rules, you give it axioms or principles to work on, and you let it do the calculation. You work with the in-built algorithms of the browser and of CSS itself.

This is all possible thanks to improvements to CSS like calc, flexbox and grid. Jen calls this approach intrinsic web design. Last year, I liveblogged her excellent talk at An Event Apart called Designing Intrinsic Layouts.

Utopia feels like it has the same mindset as algorithmic layout design and intrinsic web design. Trys and James are building on the great work already out there, which brings me to the final property of Utopia that appeals to me…

It’s iterative

There isn’t actually much that’s new in Utopia. It’s a combination of existing techniques. I like that. As I said recently:

I’m a great believer in the HTML design principle, Evolution Not Revolution:

It is better to evolve an existing design rather than throwing it away.

First of all, Utopia uses the idea of modular scales in typography. Tim Brown has been championing this idea for years.

Then there’s the idea of typography being fluid and responsive—just like Jason Pamental has been speaking and writing about.

On the code side, Utopia wouldn’t be possible without the work of Mike Reithmuller and his breakthroughs on responsive and fluid typography, which led to Tim’s work on CSS locks.

Utopia takes these building blocks and combines them. So if you’re wondering if it would be a good tool for one of your projects, you can take an equally iterative approach by asking some questions…

Are you using fluid type?

Do your font-sizes increase in proportion to the width of the viewport? I don’t mean in sudden jumps with @media breakpoints—I mean some kind of relationship between font size and the vw (viewport width) unit. If so, you’re probably using some kind of mechanism to cap the minimum and maximum font sizes—CSS locks.

I’m using that technique on Resilient Web Design. But I’m not changing the relative difference between different sized elements—body copy, headings, etc.—as the screen size changes.

Are you using modular scales?

Does your type system have some kind of ratio that describes the increase in type sizes? You probably have more than one ratio (unlike Resilient Web Design). The ratio for small screens should probably be smaller than the ratio for big screens. But rather than jump from one ratio to another at an arbitrary breakpoint, Utopia allows the ratio to be fluid.

So it’s not just that font sizes are increasing as the screen gets larger; the comparative difference is also subtly changing. That means there’s never a sudden jump in font size at any time.

Are you using custom properties?

A technical detail this, but the magic of Utopia relies on two powerful CSS features: calc() and custom properties. These two workhorses are used by Utopia to generate some CSS that you can stick at the start of your stylesheet. If you ever need to make changes, all the parameters are defined at the top of the code block. Tweak those numbers and watch everything cascade.

You’ll see that there’s one—and only one—media query in there. This is quite clever. Usually with CSS locks, you’d need to have a media query for every different font size in order to cap its growth at the maximum screen size. With Utopia, the maximum screen size—100vw—is abstracted into a variable (a custom property). The media query then changes its value to be the upper end of your CSS lock. So it doesn’t matter how many different font sizes you’re setting: because they all use that custom property, one single media query takes care of capping the growth of every font size declaration.

If you’re already using CSS locks, modular scales, and custom properties, Utopia is almost certainly going to be a good fit for you.

If you’re not yet using those techniques, but you’d like to, I highly recommend using Utopia on your next project.

Tuesday, February 11th, 2020

Fluid scale and tokens: a match made in heaven - Andy Bell

Andy takes Utopia for a spin—it very much matches his approach.

Utopia

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.

Monday, February 10th, 2020

Custom Styling Form Inputs With Modern CSS Features | CSS-Tricks

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.

Friday, January 31st, 2020

Union

The nation I live in has decided to impose sanctions on itself. The government has yet to figure out the exact details. It won’t be good.

Today marks the day that the ironically-named Kingdom of Great Britain and Northern Ireland officially leaves the European Union. Nothing will change on a day to day basis (until the end of this year, when the shit really hits the fan).

Looking back on 2019, I had the pleasure and privelige of places that will remain in the European Union. Hamburg, Düsseldorf, Utrecht, Miltown Malbay, Kinsale, Madrid, Amsterdam, Paris, Frankfurt, Antwerp, Berlin, Vienna, Cobh.

Maybe I should do a farewell tour in 2020.

Grüße aus Hamburg!

Auf Wiedersehen, Düsseldorf!

Going for a stroll in Utrecht at dusk.

The road to Miltown.

Checked in at Kinsale Harbour. with Jessica

Checked in at La Casa del Bacalao. Tapas! — with Jessica

Hello Amsterdam!

Indoor aviation.

Guten Tag, Frankfurt.

Catch you later, Antwerp.

The Ballardian exterior of Tempelhof.

Losing my religion.

Boats in Cobh.

Wednesday, November 27th, 2019

Case Study: lynnandtonic.com 2019 refresh - lynnandtonic.com

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!

Tuesday, November 12th, 2019

CSS for all

There have been some great new CSS properties and values shipping in Firefox recently.

Miriam Suzanne explains the difference between the newer revert value and the older inherit, initial and unset values in a video on the Mozilla Developer channel:

display: revert;

In another video, Jen describes some new properties for styling underlines (on links, for example):

text-decoration-thickness:  0.1em;
text-decoration-color: red;
text-underline-offset: 0.2em;
text-decoration-skip-ink: auto;

Great stuff!

As far as I can tell, all of these properties are available to you regardless of whether you are serving your website over HTTP or over HTTPS. That may seem like an odd observation to make, but I invite you to cast your mind back to January 2018. That’s when the Mozilla Security Blog posted about moving to secure contexts everywhere:

Effective immediately, all new features that are web-exposed are to be restricted to secure contexts. Web-exposed means that the feature is observable from a web page or server, whether through JavaScript, CSS, HTTP, media formats, etc. A feature can be anything from an extension of an existing IDL-defined object, a new CSS property, a new HTTP response header, to bigger features such as WebVR.

(emphasis mine)

Buzz Lightyear says to Woody: Secure contexts …secure contexts everywhere!

Despite that “effective immediately” clause, I haven’t observed any of the new CSS properties added in the past two years to be restricted to HTTPS. I’m glad about that. I wrote about this announcement at the time:

I am in total agreement that we should be encouraging everyone to switch to HTTPS. But requiring HTTPS in order to use CSS? The ends don’t justify the means.

If there were valid security reasons for making HTTPS a requirement, I would be all for enforcing this. But these are two totally separate areas. Enforcing HTTPS by withholding CSS support is no different to enforcing AMP by withholding search placement.

There’s no official word from the Mozilla Security Blog about any change to their two-year old “effective immediately” policy, and the original blog post hasn’t been updated. Maybe we can all just pretend it never happened.

Monday, July 1st, 2019

8 DOM features you didn’t know existed - LogRocket Blog

If you ignore the slightly insulting and condescending clickbaity title, this is a handy run-down of eight browser features with good support:

  1. extra arguments in addEventListener(),
  2. scrollTo(),
  3. extra arguments in setTimeout() and setInterval(),
  4. the defaultChecked property for checkboxes,
  5. normalize() and wholeText for strings of text,
  6. insertAdjacentElement() and insertAdjacentText(),
  7. event.detail, and
  8. scrollHeight and scrollWidth.

Tuesday, May 28th, 2019

How Ireland became Europe’s data watchdog - BBC News

The coming GDPR storm:

Ireland’s Data Protection Commissioner, Helen Dixon, is expected to circulate her decisions on some cases by July or August, with final rulings made by the end of the year.

(That’s my sister-in-law, that is.)