Tag: Styling

Styling in the Shadow DOM With CSS Shadow Parts 

Safari 13.1 just shipped support for CSS Shadow Parts. That means the ::part() selector is now supported in Chrome, Edge, Opera, Safari, and Firefox. We’ll see why it’s useful, but first a recap on shadow DOM encapsulation…

The benefits of shadow DOM encapsulation

I work at giffgaff where we have a wide variety of CSS code that has been written by many different people in many different ways over the years. Let’s consider how this might be problematic. 

Naming collisions

Naming collisions between classes can easily crop up in CSS. One developer might create a class name like .price. Another developer (or even the same one) might use the same class name, without knowing it.

CSS won’t alert you to any error here. Now, any HTML elements with this class will receive the styling intended for two completely different things.

Shadow DOM fixes this problem. CSS-in-JS libraries, like Emotion and styled-components, also solve this issue in a different way by generating random class names, like .bwzfXH. That certainly does help avoid conflicts! However, CSS-in-JS doesn’t prevent anybody from breaking your component in other ways. For example…

Base styles and CSS resets

Styles can be applied using HTML element selectors like <button> and <div>. These styles could break a component. Shadow DOM is the only thing that offers (almost) full encapsulation — you can rest assured that your component will look the same, even in a messy  !important  strewn codebase because each component is encapsulated.

/* This will have no effect on buttons inside shadow DOM */ button { background-color: lime !important; }

I wouldn’t say it’s good practice to style elements this way, but it happens. Even it does, those styles will have no effect on the shadow DOM.

It’s worth noting that inheritable styles like color, font and line-height are still inherited in a shadow DOM. To prevent that, use all: initial  or, preferably, all: revert once it has better browser support.

Let’s look at a common example of CSS applied directly to HTML elements. Consider this code from Eric Meyer’s reset

html, body, div, span, applet, object, iframe, h1, h2, h3, h4, h5, h6, p, blockquote, pre, a, abbr, acronym, address, big, cite, code, del, dfn, em, img, ins, kbd, q, s, samp, small, strike, strong, sub, sup, tt, var, b, u, i, center, dl, dt, dd, ol, ul, li, fieldset, form, label, legend, table, caption, tbody, tfoot, thead, tr, th, td, article, aside, canvas, details, embed,  figure, figcaption, footer, header, hgroup,  menu, nav, output, ruby, section, summary, time, mark, audio, video {   margin: 0;   padding: 0;   border: 0;   font-size: 100%;   font: inherit;   vertical-align: baseline; }

What if the component we’re working with makes use of the user agent’s default values for margin and padding? This reset might cause it to appear broken since those defaults are effectively wiped out.

Shadow DOM is a way to avoid these problems. Shadow DOM allows us to feel fully confident that a component will render as expected, regardless of what codebase it ends up in. Equally, none of the code meant only for a component can inadvertently affect anything else — all without resorting to onerous class naming conventions. Shadow DOM offers a level of encapsulation that can’t be achieved any other way.

Encapsulation is great, but we also want our components to be themeable and customizable. That’s been made far easier with the ::part selector. 

Styling shadow DOM with ::part()

Until now, the only way for CSS to modify the styling of a custom element from outside of the shadow DOM was to use CSS custom properties. In a strict design system where you only want to allow limited changes, that might be ideal. If you want your component to be more versatile, it creates a problem. Every CSS property you want to offer up for styling needs to be defined using a custom property. Just the sound of that seems tedious.

The situation is compounded further if we want to style a component differently based on pseudo-classes, like :hover. Basically, we end up with loads of custom properties. Let’s look at an example from Ionic, an open source set of web components. Just look at all the custom properties defined on the Ionic button component.

Go ahead, I’ll wait.

I counted 23 custom properties. Needless to say, that’s less than ideal.

Here’s an example using ::part() to style the element instead. 

In this Pen, I’m simply changing the color, border and background-color properties, but I could use whatever I want without being constrained by what custom properties have been defined. Notice that I can also style different states of the part using pseudo-classes, like :hover and :focus.

The entire component in this button example is being exposed for styling, but if your web component consists of multiple HTML elements, you can expose only selected parts of the component to this sort of styling — hence the name ::part. This stops users of the component from styling any arbitrary element inside the shadow tree. It is up the the component author to expose the parts of the component they explicitly want to. Other parts of the component can be kept visually uniform or make use of custom properties for a more minimal customizability. 

So, how do we set this up for our own components? Let’s look at using ::part to make certain elements of a web component eligible for styling. All we do is add a part attribute on the element we want to be exposed.

<div part="box">...</div>   <button>Click me</button>

In this example the div is customizable with the full gamut of CSS — any CSS property can be changed. The button, however, is locked down — it cannot be visually changed by anybody except the component author.

And the same way an HTML element can have multiple classes, an element can have multiple part names: 

<div part="box thing">...</div>

So that’s what we get with ::part: by exposing “parts” of an element we can provide some flexibility in how a web component is used while exercising protection in other areas. Whether it’s your design system, a component library, or what have you, the fact that CSS Shadow Parts are becoming mainstream gives us yet another exciting tool to work with.

The post Styling in the Shadow DOM With CSS Shadow Parts  appeared first on CSS-Tricks.

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Custom Styling Form Inputs With Modern CSS Features

It’s entirely possible to build custom checkboxes, radio buttons, and toggle switches these days, while staying semantic and accessible. We don’t even need a single line of JavaScript or extra HTML elements! It’s actually gotten easier lately than it has been in the past. Let’s take a look.

Here’s where we’ll end up:

Things sure have gotten easier than they were!

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.

Let’s look at the HTML

Nothing special here. We can style our inputs with just this HTML:

<!-- Checkbox --> <input type="checkbox">  <!-- Radio --> <input type="radio">  <!-- Switch --> <input type="checkbox" class="switch">

That’s it for the HTML part, but of course it’s recommended to have name and id attributes, plus a matching <label> element:

<!-- Checkbox --> <input type="checkbox" name="c1" id="c1"> <label for="c1">Checkbox</label>  <!-- Radio --> <input type="radio" name="r1" id="r1"> <label for="r1">Radio</label>  <!-- Switch --> <input type="checkbox" class="switch" name="s1" id="s1"> <label for="s1">Switch</label>

Getting into the styling 

First of all, we check for the support of appearance: none;, including it’s prefixed companions. The appearance property is key because it is designed to remove a browser’s default styling from an element. If the property isn’t supported, the styles won’t apply and default input styles will be shown. That’s perfectly fine and a good example of progressive enhancement at play.

@supports(-webkit-appearance: none) or (-moz-appearance: none) {   input[type='checkbox'],   input[type='radio'] {     -webkit-appearance: none;     -moz-appearance: none;   } }

As it stands today, appearance  is a working draft, but here’s what support looks like:

This browser support data is from Caniuse, which has more detail. A number indicates that browser supports the feature at that version and up.

Desktop

Chrome Firefox IE Edge Safari
82* 74* No 79* TP*

Mobile / Tablet

Android Chrome Android Firefox Android iOS Safari
79* 68* 76* 13.3*

Like links, we’ve gotta consider different interactive states with form elements. We’ll consider these when styling our elements:

  • :checked
  • :hover
  • :focus
  • :disabled

For example, here’s how we can style our toggle input, create the knob, and account for the :checked state:

/* The toggle container */ .switch {   width: 38px;   border-radius: 11px; }  /* The toggle knob */ .switch::after {   left: 2px;   top: 2px;   border-radius: 50%;   width: 15px;   height: 15px;   background: var(--ab, var(--border));   transform: translateX(var(--x, 0)); }  /* Change color and position when checked */ .switch:checked {   --ab: var(--active-inner);   --x: 17px; }  /* Drop the opacity of the toggle knob when the input is disabled */ .switch:disabled:not(:checked)::after {   opacity: .6; }

We are using the <input> element like a container. The knob inside of the input is created with the ::after pseudo-element. Again, no more need for extra markup!

If you crack open the styles in the demo, you’ll see that we’re defining some CSS custom properties because that’s become such a nice way to manage reusable values in a stylesheet:

@supports(-webkit-appearance: none) or (-moz-appearance: none) {   input[type='checkbox'],   input[type='radio'] {     --active: #275EFE;     --active-inner: #fff;     --focus: 2px rgba(39, 94, 254, .25);     --border: #BBC1E1;     --border-hover: #275EFE;     --background: #fff;     --disabled: #F6F8FF;     --disabled-inner: #E1E6F9;   } }

But there’s another reason we’re using custom properties — they work well for updating values based on the state of the element! We won’t go into full detail here, but here’s an example how we can use custom properties for different states.

/* Default */ input[type='checkbox'], input[type='radio'] {   --active: #275EFE;   --border: #BBC1E1;   border: 1px solid var(--bc, var(--border)); }  /* Override defaults */ input[type='checkbox']:checked, input[type='radio']:checked {   --b: var(--active);   --bc: var(--active); }    /* Apply another border color on hover if not checked & not disabled */ input[type='checkbox']:not(:checked):not(:disabled):hover, input[type='radio']:not(:checked):not(:disabled):hover {   --bc: var(--border-hover); }

For accessibility, we ought to add a custom focus style. We are removing the default outline because it can’t be rounded like the rest of the things we’re styling. But a border-radius along with a box-shadow can make for a rounded style that works just like an outline.

input[type='checkbox'], input[type='radio'] {   --focus: 2px rgba(39, 94, 254, .25);   outline: none;   transition: box-shadow .2s; }  input[type='checkbox']:focus, input[type='radio']:focus {   box-shadow: 0 0 0 var(--focus); }

It’s also possible to align and style the <label> element which directly follows the <input> element in the HTML:

<input type="checkbox" name="c1" id="c1"> <label for="c1">Checkbox</label>
input[type='checkbox'] + label, input[type='radio'] + label {   display: inline-block;   vertical-align: top;   /* Additional styling */ }  input[type='checkbox']:disabled + label, input[type='radio']:disabled + label {     cursor: not-allowed; }

Here’s that demo again:

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.

All in all, this is a much more pleasant developer experience than we’ve had to deal with in the past!

The post Custom Styling Form Inputs With Modern CSS Features appeared first on CSS-Tricks.

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Thinking Through Styling Options for Web Components

Where do you put styles in web components?

I’m assuming that we’re using the Shadow DOM here as, to me, that’s one of the big draws of a web component: a platform thing that is a uniquely powerful thing the platform can do. So this is about defining styles for a web component in a don’t-leak-out way, and less so a way to get global styles to leak in (although that’s very interesting as well, which can be done via custom properties which we’ll look at later in the article).

If you’re building the template inside the JavaScript — which is nice because of template literals and how we can sprinkle our data into the template nicely — you need access to those styles in JavaScript.

const template = `   <style>$  {styles}</style>   <div class="$  {class}">     <h2>$  Thinking Through Styling Options for Web Components</h2>     $  {content}   </div> `;

Where does that style variable come from? Maybe also a template literal?

const style = `   :host {     background: white;   }   h2 {     font: 900 1.5rem/1.1 -system-ui, sans-serif;   } `;

I guess that’s fine, but it makes for a big messy block of code just dunked somewhere in the class where you’re trying to build this web component.

Another way is to <template> the template and make a <style> block part of it.

<template id="card-template">   <style>     :host {       background: white;     }     h2 {       font: 900 1.5rem/1.1 -system-ui, sans-serif;     }   </style>    <div id="card-hook">     <h2 id="title-hook"></h2>     <p id="desc-hook"></p>   </div> </template>

I can see the appeal with this because it keeps HTML in HTML. What I don’t love about it is that you have to do a bunch of manual shadowRoot.querySelector("#title-hook").innerHTML = myData.title; work in order to flesh out that template. That doesn’t feel like a convenient template. I also don’t love that you need to just chuck this template somewhere in your HTML. Where? I dunno. Just chuck it in there. Chuck it.

The CSS is moved out of the JavaScript too, but it just moved from one awkward location to another.

If we wanted to keep the CSS in a CSS file, we can sorta do that like this:

<template id="card-template">   <style>     @import "/css/components/card.css";   </style>    <div id="card-hook">     <h2 id="title-hook"></h2>     <p id="desc-hook"></p>   </div> </template>

(The use of <link rel="import" type="css" href=""> is deprecated, apparently.)

Now we have @import which is an extra HTTP Request, and notorious for being a performance hit. An article by Steven Lambert says it clocked in at half a second slower. Not ideal. I don’t suppose it would be much better to do this instead:

class MyComponent extends HTMLElement {        constructor() {     super();     this.attachShadow({ mode: "open" });      fetch('/css/components/card.css')       .then(response => response.text())       .then(data => {         let node = document.createElement('style');         node.innerHTML = data;         document.body.appendChild(node);       });   }    // ... }

Seems like that would potentially be a Flash-of-Unstyled-Web-Component? I guess I should get off my butt and test it.

Now that I’m digging into this again, it seems like ::part has gotten some steam (explainer). So I can do…

const template = `   <div part="card">     <h2>$  Thinking Through Styling Options for Web Components</h2>     $  {content}   </div> `;

…then write styles in a global stylesheet that only apply inside that Shadow DOM, like:

my-card::part(card) {   background: black;   color: white; }

…which has a smidge of browser support, but maybe not enough?

These “part” selectors can only touch the exact element it’s connected to. You’d have to do all your styling by applying a part name to every single DOM node and then styling each entirely on its own. That’s no fun, particularly because the appeal of the Shadow DOM is this isolated styling environment in which we’re supposed to be able to write looser CSS selectors and not be worried our h2 { } style is going to leak all over the place.

Looks like if native CSS modules becomes a thing, that will be the most helpful thing that could happen.

import styles from './styles.css';  class MyElement extends HTMLElement {   constructor() {     this.attachShadow({mode: open});     this.shadowRoot.adoptedStyleSheets = [styles];   } }

I’m not sure, however, if this is any sort of performance boost. Seems like it would be a wash between this and @import. I have to say I prefer the clarity and syntax with native CSS modules. It’s nice to be writing JavaScript when working with JavaScript.

Constructable Stylesheets also look helpful for sharing a stylesheet across multiple components. But the CSS modules approach looks like it could also do that since the stylesheet has already become a variable at that point.

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The Current State of Styling Selects in 2019

Best I could tell from the last time I compiled the most wished-for features of CSS, styling form controls was a major ask. Top 5, I’d say. And of the native form elements that people want to style, Greg Whitworth has some data that the <select> element is more requested than any other element — more than double the next element — and it’s the one developers most often customize in some way.

Developers clearly want to style select dropdowns.

You actually do a little. Perhaps more than you realize.

The best crack at this out there comes from Scott Jehl over on the Filament Group blog. I’ll embed a copy here so it’s easy to see:

See the Pen
select-css by Scott/Filament Group
by Chris Coyier (@chriscoyier)
on CodePen.

Notably, this is an entirely cross-browser solution. It’s not something limited to only the most progressive desktop browsers. There are some visual differences across browsers and platforms, but overall it’s pretty consistent and gives you a baseline from which to further customize it.

That’s just the “outside”

Open the select. Hmm, it looks and behaves like you did nothing to it at all.

Styling a <select> doesn’t do anything to the opened dropdown of items. (Screenshot from macOS Chrome)

Some browsers do let you style the inside, but it’s very limited. Any time I’ve gone down this road, I’ve had a bad time getting things cross-browser compliant.

Firefox letting me set the background of the dropdown and the color of a hovered option.

Greg’s data shows that only 14% (third place) of developers found styling the outside to be the most painful part of select elements. I’m gonna steal his chart because it’s absolutely fascinating:

Frustration % Count
Not being able to create a good user experience for searching within the list 27.43% 186
Not being able to style the <option> element to the extent that you needed to 17.85% 121
Not being able to style the default state (dropdown arrow, etc.) 14.01% 95
Not being able to style the pop-up window on desktop (e.g. the border, drop shadows, etc.) 11.36% 77
Insertion of content beyond simple text in the <select> control or its <option>s 11.21% 76
Insertion of arbitrary HTML content in an <option> element 7.82% 53
Not being able to create distinctive unselected/placeholder style and behavior 3.39% 23
Being able to generate new options from a large dataset while the popup is open 3.10% 21
Not being able to style the currently selected <option>(s) to the extent you needed to 1.77% 12
Not being able to style the pop-up window on mobile 1.03% 7
Being able to have the options automatically repeat on scroll (i.e., if you have an list of options 1 – 100, as you reach 100 rather than having the user scroll back to the top, have 1 show up below 100) 1.03% 7

Boiled down, the most painful parts of styling selects are:

  • Search
  • Styling the open dropdown, including the individual options, including more than just text
  • Updating the element without closing it
  • Styling for cases where “nothing” is selected and when an item is selected

I’m surprised multi-select didn’t make the cut. Maybe it’s not on the table for <select> since it wouldn’t be backwards-compatible?

Browser evolution

Edge recently announced they are improving the look of form controls, but no word just yet on standards or how to customize them.

Select styles in Edge/Chromium before (left) and after (right)

It seems like there is good momentum, though. If you want more information and to follow along with all this progress (I know I will!):

The post The Current State of Styling Selects in 2019 appeared first on CSS-Tricks.

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Styling Based on Scroll Position

Rik Schennink documents a system for being able to write CSS selectors that style a page when it has scrolled to a certain point. If you’re like me, you’re already on the lookout for document.addEventListener('scroll' ... and being terrified about performance. Rik gets to that right away by both debouncing the function as well as marking the event as passive.

The end result is a data-scroll attribute on the <html> element that can be used in the CSS. Meaning if you’re scrolled to 640px down the page, you have <html data-scroll="640"> and could write a selector like:

html:not([data-scroll='0']) {   body {     padding-top: 3em;   }   header {     position: fixed;   } }

See the Pen
Writing Dumb JS 🧟‍♂️ and Smart CSS 👩‍🔬
by Rik Schennink (@rikschennink)
on CodePen.

Unfortunately, we don’t have greater than (>) less than (<) selectors in CSS for things like numbered attributes, so the CSS styling potential is fairly limited here. You might ultimately need to update the JavaScript function such that it applies other classes or data attributes based on your math. But you’ll already be set up for good performance here.

“Apply styles when the user has scrolled away from the top” is a legit use case. It makes me think of a once function (like we have in jQuery) where any scroll event would only be triggered once and then not again. They scrolled! So, by definition, they aren’t at the top anymore! But that doesn’t deal with when they scroll back to the top.

I find it generally more useful to use IntersectionObserver for styling things based on scroll position. With it, you can do things like, “has this element been scrolled into view or beyond,” which is generically useful and can be used for scrolled-away-from-top stuff too.

Here’s an example that adds or removes a class if a user has scrolled past a hidden pixel positioned at 500px down the page.

See the Pen
Fixed Header with IntersectionObserver
by Chris Coyier (@chriscoyier)
on CodePen.

That’s performant as well, avoiding any scroll event handlers at all.

And speaking of IntersectionObserver, check out “Trust is Good, Observation is Better—Intersection Observer v2”.

The post Styling Based on Scroll Position appeared first on CSS-Tricks.

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Styling a Web Component

This confused me for a bit here so I’m writing it out while it’s fresh in mind. Just because you’re using a web component doesn’t mean the styles of it are entirely isolated. You might have content within a web component that is styled normally along with the rest of your website. Like this:

See the Pen yGaNKr by Chris Coyier (@chriscoyier) on CodePen.

That <whats-up> element isolated the JavaScript-powered functionality of itself by attaching a click handler to the <button> inside of it. But the styling of that button comes from global CSS applied to that page.

But let’s say we move that <button> into the web component, so we can use <whats-up> all by itself. We could do that by .innerHTML‘ing the web component (I suppose because it’s really a “custom element”):

See the Pen Web Component with Global Styles (because no Shadow DOM) by Chris Coyier (@chriscoyier) on CodePen.

Again, entirely styled by the global CSS. Cool. That may be desirable. It also might not be desirable. Perhaps you’re looking to web components to isolate styles for you. Web components can do that via the Shadow DOM. Here’s that same component, using Shadow DOM instead:

See the Pen Web Component with Local Styles by Chris Coyier (@chriscoyier) on CodePen.

Note that the functionality still works (although we had to querySelector<code> through the <code>shadowRoot), but we’ve totally lost the global styling. The Shadow DOM boundry (shadow root) prevents styling coming in or going out (sorta like an iframe).

Shadow Root

There is no global way to penetrate that boundary that I’m aware of, so if you want to bring styles in, you gotta bring them into the template.

See the Pen Web Component with Local Styles by Chris Coyier (@chriscoyier) on CodePen.

This would be highly obnoxious if you both really wanted to use the Shadow DOM but also wanted your global styles. It’s funny that there is a Shadow DOM “mode” for open and closed for allowing or disallowing JavaScript in and out, but not CSS.

If that’s you, you’ll probably need to @import whatever global stylesheets you can to bring in those global styles and hope they are cached and the browser is smart about it in such a way that it isn’t a big performance hit.

I’ll use CodePen’s direct link to CSS feature to import the styles from the Pen itself into the web component:

See the Pen Web Component with Local Styles by Chris Coyier (@chriscoyier) on CodePen.

Another important thing to know is that CSS custom properties penetrate the Shadow DOM! That’s right, they do. You can select the web component in the CSS and set them there:

See the Pen Web Component with Custom Properties by Chris Coyier (@chriscoyier) on CodePen.

The post Styling a Web Component appeared first on CSS-Tricks.

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Styling a Select Like It’s 2019

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The Current State of Styling Scrollbars

If you need to style your scrollbars right now, one option is to use a collection of ::webkit prefixed CSS properties.

See the Pen CSS-Tricks Almanac: Scrollbars by Chris Coyier (@chriscoyier) on CodePen.

Sadly, that doesn’t help out much for Firefox or Edge, or the ecosystem of browsers around those.

But if that’s good enough for what you need, you can get rather classy with it:

See the Pen Custom Scrollbar styling by Devstreak (@devstreak) on CodePen.

There are loads of them on CodePen to browse. It’s a nice thing to abstract with a Sass @mixin as well.

There is good news on this front! The standards bodies that be have moved toward a standardizing methods to style scrollbars, starting with the gutter (or width) of them. The main property will be scrollbar-gutter and Geoff has written it up here. Hopefully Autoprefixer will help us as the spec is finalized and browsers start to implement it so we can start writing the standardized version and get any prefixed versions from that.

But what if we need cross-browser support?

(more…)

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Simplify Styling with Functional CSS

There is no doubt that “functional CSS” resonates strongly with some people. If that term is new to you, I belive it’s come to mean the same thing as “Atomic CSS” as defined by John Polacek here. Harry Nicholls likens it to a function that can only produce one result (although I’d call that a pure function or pure component), but instead of a return value being entirely predictable based on inputs, it is an application of style that only does one thing.

I’m of two minds here. People say how fast they can work this way. Great! They like how predictable the applied styles are. Great! I can understand how a tiny stylesheet that doesn’t grow over time is appealing as well.

At the same time, I haven’t seen writing about other styling concerns. What happens with big redesigns? Is it about the same, time- and difficulty-wise, or do you spend more time tearing down all those classes? What happens when you need a style that isn’t available? Write your own? Or does that ruin the spirit of all this and put you in dangerous territory? How intense can all the class names get? I can think of areas I’ve styled that have three or more media queries that dramatically re-style an element. Putting all that information in HTML seems like it could get awfully messy. Is consistency harder or easier? I get that “p5” might be a useful way to apply an abstract amount of padding, but you still need to sprinkle it all over your codebase and know when to use it, right?

The closest I’ve been to being convinced about it was hearing from Adam just how configurable Tailwind is. In any case, I find this all endless fascinating and, if you love it, more power to ya.

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