Tag: News

Platform News: Using :focus-visible, BBC’s New Typeface, Declarative Shadow DOMs, A11Y and Placeholders

There’s a whole lot of accessibility in this week’s news, from the nuances of using :focus-visible and input placeholders, to accessible typefaces and a Safari bug with :display: contents. Plus, a snippet for a bare-bones web component that supports style encapsulation.

Now may be a good time to start using :focus-visible

The CSS :focus-visible pseudo-class replaces :focus as the new way to create custom focus indicators for keyboard users. Chrome recently switched from :focus to :focus-visible in the user agent stylesheet and, as a result of that change, the default focus ring is no longer shown when the user clicks or taps a button.

When switching from :focus to :focus-visible, consider backwards compatibility. Your keyboard focus indicators should be clearly visible in all browsers, not just the ones that support :focus-visible. If you only style :focus-visible, non-supporting browsers will show the default focus ring which, depending on your design, “may not be sufficiently clear or visible at all.”

button {   background: white; }  button:focus-visible {   outline: none;   background: #ffdd00; /* gold */ }

A good way to start using :focus-visible today is to define the focus styles in a :focus rule and then immediately undo these same styles in a :focus:not(:focus-visible) rule. This is admittedly not the most elegant and intuitive pattern, but it works well in all browsers:

  • Browsers that don’t support :focus-visible use the focus styles defined in the :focus rule and ignore the second style rule completely (because :focus-visible is unknown to them).
  • In browsers that do support :focus-visible, the second style rule reverts the focus styles defined in the :focus rule if the :focus-visible state isn’t active as well. In other words, the focus styles defined in the :focus rule are only in effect when :focus-visible is also active.
button:focus {   outline: none;   background: #ffdd00; /* gold */ }  button:focus:not(:focus-visible) {   background: white; /* undo gold */ }

The BBC created a more accessible typeface

The BBC created their own custom typeface called Reith (named after the BBC’s founder Sir John Reith). Their goal was to create a font that supports multiple languages and is easier to read, especially on small devices. The font was tested with mixed-ability user groups (dyslexia and vision impairment) and across different screen sizes.

We [the BBC] were using Helvetica or Arial. We also had Gill Sans as the corporate typeface. These typefaces were designed a hundred years ago for the printed page [and] don’t perform well on today’s modern digital screens.

Reith Sans can bee seen in use on BBC Sport

Note: If you’d like to inspect Reith Sans and Reith Serif in Wakamai Fondue, you can quickly access the URLs of the WOFF2 files in the “All fonts on page” section of the Fonts pane in Firefox’s DOM inspector on BBC’s website.

display: contents is still not accessible in Safari

The CSS display: contents value has been supported in browsers since 2018. An element with this value “does not generate any boxes” and is effectively replaced by its children. This is especially useful in flex and grid layouts, where the contents value can be used to “promote” more deeply nested elements to flex/grid items while retaining a semantic document structure.

Source: Manuel Rego Casasnovas

Unfortunately, this feature originally shipped with an implementation bug that removed the element from the browser’s accessibility tree. For example, applying display: contents to a <ul> element resulted in that element no longer mentioned by screen readers. Since then, this bug has been fixed in Firefox and Chrome (in the latest version).

View on CodePen

In Chrome and Firefox, the screen reader informs the user that the “Main, navigation” contains a “list, 2 items.” In Safari, the latter part is missing because the <ul> and <li> elements are not present in the accessibility tree. Until Apple fixes this bug in Safari, be careful when using the contents value on semantic elements and test in screen readers to confirm that your pages are accessible in Safari as well.

Set opacity when overriding the color of placeholder text

Accessibility experts recommend avoiding placeholders if possible because they can be confused for pre-populated text and disappear when the user starts entering a value. However, many websites (including Wikipedia and GOV.UK) use placeholders in simple web forms that contain only a single input field, such as a search field.

The subscription form for the CSS-Tricks newsletter uses a placeholder in the email field

Placeholders can be styled via the widely supported ::placeholder pseudo-element. If your design calls for a custom color for placeholder text, make sure to specify both color and opacity. The latter is needed for Firefox, which applies opacity: 0.54 to ::placeholder by default. If you don’t override this value, your placeholder text may have insufficient contrast in Firefox.

.search-field::placeholder {   color: #727272;   opacity: 1; /* needed for Firefox */ }
The placeholder text on eBay’s website is lighter in Firefox and doesn’t meet the minimum contrast requirement of 4.5:1

Declarative shadow DOM could help popularize style encapsulation

One of the key features of shadow DOM is style encapsulation, wherein the outer page’s style rules don’t match elements inside the shadow tree, and vice versa. In order to use this feature, you need to attach a shadow DOM tree to an element (usually a custom element, like <my-element>) and copy the element’s template (usually from a <template> element in the DOM) to the element’s newly created shadow DOM.

These steps can only be performed in JavaScript. If you’re only interested in style encapsulation and don’t need any dynamic functionality for your element, here is the minimum amount of JavaScript required to create a custom element with a shadow DOM:

customElements.define(   "my-element",   class extends HTMLElement {     constructor() {       super();        // find <template id="my-template"> in the DOM       let template = document.getElementById("my-template");        // make a copy of the template contents…       let content = template.content.cloneNode(true);        // …and inject it into <my-element>’s shadow DOM       this.attachShadow({ mode: "open" }).appendChild(content);     }   } );

For an example of style encapsulation, see Miriam Suzanne’s <media-object> element on CodePen. The scoped styles are located in the <template> element in the HTML pane. Notice how this CSS code can use simple selectors, such as article, that only match elements inside <media-object>’s shadow DOM.

JavaScript may soon no longer be required to create this type of style encapsulation in modern browsers. Earlier this week, Chrome became the first browser to ship Google’s Declarative Shadow DOM proposal. If it becomes a standard, this feature will also make it possible to use Shadow DOM in combination with server-side rendering.


The post Platform News: Using :focus-visible, BBC’s New Typeface, Declarative Shadow DOMs, A11Y and Placeholders appeared first on CSS-Tricks.

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Platform News: Rounded Outlines, GPU-Accelerated SVG Animations, How CSS Variables Are Resolved

In the news this week, Firefox gets rounded outlines, SVG animations are now GPU-accelerated in Chrome, there are no physical units in CSS, The New York Times crossword is accessible, and CSS variables are resolved before the value is inherited.

Let’s jump in the news!

Rounded outlines are coming to Firefox

The idea to have the outline follow the border curve has existed ever since it became possible to create rounded borders via the border-radius property in the mid 2000s. It was suggested to Mozilla, WebKit, and Chromium over ten years ago, and it’s even been part of the CSS UI specification since 2015:

The parts of the outline are not required to be rectangular. To the extent that the outline follows the border edge, it should follow the border-radius curve.

Fast-forward to today in 2021 and outlines are still rectangles in every browser without exception:

But this is finally starting to change. In a few weeks, Firefox will become the first browser with rounded outlines that automatically follow the border shape. This will also apply to Firefox’s default focus outline on buttons.

Three sets of round yellow buttons, comparing how Chrome, Firefox, and Safari handle outlines.

Please star Chromium Issue #81556 (sign in required) to help prioritize this bug and bring rounded outlines to Chrome sooner rather than later.

SVG animations are now GPU-accelerated in Chrome

Until recently, animating an SVG element via CSS would trigger repaint on every frame (usually 60 times per second) in Chromium-based browsers. Such constant repainting can have a negative impact on the smoothness of the animation and the performance of the page itself.

The latest version of Chrome has eliminated this performance issue by enabling hardware acceleration for SVG animations. This means that SVG animations are offloaded to the GPU and no longer run on the main thread.

Side by side comparison of the Performance tab in Chrome DevTools.
In this example, the SVG circle is continuously faded in and out via a CSS animation (see code)

The switch to GPU acceleration automatically made SVG animations more performant in Chromium-based browsers (Firefox does this too), which is definitely good news for the web:

Hooray for more screen reader-accessible, progressively enhanced SVG animations and less Canvas.

There cannot be real physical units in CSS

CSS defines six physical units, including in (inches) and cm (centimeters). Every physical unit is in a fixed ratio with the pixel unit, which is the canonical unit. For example, 1in is always exactly 96px. On most modern screens, this length does not correspond to 1 real-world inch.

The FAQ page of the CSS Working Group now answers the question why there can’t be real physical units in CSS. In short, the browser cannot always determine the exact size and resolution of the display (think projectors). For websites that need accurate real-world units, the Working Group recommends per-device calibration:

Have a calibration page, where you ask the user to measure the distance between two lines that are some CSS distance apart (say, 10cm), and input the value they get. Use this to find the scaling factor necessary for that screen (CSS length divided by user-provided length).

This scaling factor can then be set to a custom property and used to compute accurate lengths in CSS:

html {   --unit-scale: 1.428; }  .box {   /* 5 real-world centimeters */   width: calc(5cm * var(--unit-scale, 1)); }

The Times crossword is accessible to screen reader users

The NYT Open team wrote about some of the improvements to the New York Times website that have made it more accessible in recent years. The website uses semantic HTML (<article>, <nav>, etc.), increased contrast on important components (e.g., login and registration), and skip-to-content links that adapt to the site’s paywall.

Furthermore, the Games team made the daily crossword puzzle accessible to keyboard and screen reader users. The crossword is implemented as a grid of SVG <rect> elements. As the user navigates through the puzzle, the current square’s aria-label attribute (accessible name) is dynamically updated to provide additional context.

Screenshot of the crossword game with an open screen reader dialog announcing what is on the screen.
The screen reader announces the clue, the number of letters in the solution, and the position of the selected square

You can play the mini crossword without an account. Try solving the puzzle with the keyboard.

CSS variables are resolved before the value is inherited

Yuan Chuan recently shared a little CSS quiz that I didn’t answer correctly because I wasn’t sure if a CSS variable (the var() function) is resolved before or after the value is inherited. I’ll try to explain how this works on the following example:

html {   --text-color: var(--main-color, black); }  footer {   --main-color: brown; }  p {   color: var(--text-color); }

The question: Is the color of the paragraph in the footer black or brown? There are two possibilities. Either (A) the declared values of both custom properties are inherited to the paragraph, and then the color property resolves to brown, or (B) the --text-color property resolves to black directly on the <html> element, and then this value is inherited to the paragraph and assigned to the color property.

Two CSS rulesets, one as Option A and the other as Option B, both showing how variables are inherited and resolved between elements.

The correct answer is option B (the color is black). CSS variables are resolved before the value is inherited. In this case, --text-color falls back to black because --main-color does not exist on the <html> element. This rule is specified in the CSS Variables module:

It is important to note that custom properties resolve any var() functions in their values at computed-value time, which occurs before the value is inherited.


The post Platform News: Rounded Outlines, GPU-Accelerated SVG Animations, How CSS Variables Are Resolved appeared first on CSS-Tricks.

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Platform News: Prefers Contrast, MathML, :is(), and CSS Background Initial Values

In this week’s round-up, prefers-contrast lands in Safari, MathML gets some attention, :is() is actually quite forgiving, more ADA-related lawsuits, inconsistent initial values for CSS Backgrounds properties can lead to unwanted — but sorta neat — patterns.

The prefers-contrast: more media query is supported in Safari Preview

After prefers-reduced-motion in 2017, prefers-color-scheme in 2019, and forced-colors in 2020, a fourth user preference media feature is making its way to browsers. The CSS prefers-contrast: more media query is now supported in the preview version of Safari. This feature will allow websites to honor a user’s preference for increased contrast.

Screenshot of the iPhone 12 landing page on Apple's website. A big red arrow points out light grey text on the page.
Apple could use this new media query to increase the contrast of gray text on its website
.pricing-info {   color: #86868b; /* contrast ratio 3.5:1 */ }  @media (prefers-contrast: more) {   .pricing-info {     color: #535283; /* contrast ratio 7:1 */   } }

Making math a first-class citizen on the web

One of the earliest specifications developed by the W3C in the mid-to-late ’90s was a markup language for displaying mathematical notations on the web called MathML. This language is currently supported in Firefox and Safari. Chrome’s implementation was removed in 2013 because of “concerns involving security, performance, and low usage on the Internet.”

If you’re using Chrome or Edge, enable “Experimental Web Platform features” on the about:flags page to view the demo.

There is a renewed effort to properly integrate MathML into the web platform and bring it to all browsers in an interoperable way. Igalia has been developing a MathML implementation for Chromium since 2019. The new MathML Core Level 1 specification is a fundamental subset of MathML 3 (2014) that is “most suited for browser implementation.” If approved by the W3C, a new Math Working Group will work on improving the accessibility and searchability of MathML.

The mission of the Math Working Group is to promote the inclusion of mathematics on the Web so that it is a first-class citizen of the web that displays well, is accessible, and is searchable.

CSS :is() upgrades selector lists to become forgiving

The new CSS :is() and :where() pseudo-classes are now supported in Chrome, Safari, and Firefox. In addition to their standard use cases (reducing repetition and keeping specificity low), these pseudo-classes can also be used to make selector lists “forgiving.”

For legacy reasons, the general behavior of a selector list is that if any selector in the list fails to parse […] the entire selector list becomes invalid. This can make it hard to write CSS that uses new selectors and still works correctly in older user agents.

In other words, “if any part of a selector is invalid, it invalidates the whole selector.” However, wrapping the selector list in :is() makes it forgiving: Unsupported selectors are simply ignored, but the remaining selectors will still match.

Unfortunately, pseudo-elements do not work inside :is() (although that may change in the future), so it is currently not possible to turn two vendor-prefixed pseudo-elements into a forgiving selector list to avoid repeating styles.

/* One unsupported selector invalidates the entire list */ ::-webkit-slider-runnable-track, ::-moz-range-track {   background: red; }  /* Pseudo-elements do not work inside :is() */ :is(::-webkit-slider-runnable-track, ::-moz-range-track) {   background: red; }  /* Thus, the styles must unfortunately be repeated */ ::-webkit-slider-runnable-track {   background: red; } ::-moz-range-track {   background: red; }

Dell and Kraft Heinz sued over inaccessible websites

More and more American businesses are facing lawsuits over accessibility issues on their websites. Most recently, the tech corporation Dell was sued by a visually impaired person who was unable to navigate Dell’s website and online store using the JAWS and VoiceOver screen readers.

The Defendant fails to communicate information about its products and services effectively because screen reader auxiliary aids cannot access important content on the Digital Platform. […] The Digital Platform uses visual cues to convey content and other information. Unfortunately, screen readers cannot interpret these cues and communicate the information they represent to individuals with visual disabilities.

Earlier this year, Kraft Heinz Foods Company was sued for failing to comply with the Web Content Accessibility Guidelines on one of the company’s websites. The complaint alleges that the website did not declare a language (lang attribute) and provide accessible labels for its image links, among other things.

In the United States, the Americans with Disabilities Act (ADA) applies to websites, which means that people can sue retailers if their websites are not accessible. According to the CEO of Deque Systems (the makers of axe), the recent increasing trend of web-based ADA lawsuits can be attributed to a lack of a single overarching regulation that would provide specific compliance requirements.

background-clip and background-origin have different initial values

By default, a CSS background is painted within the element’s border box (background-clip: border-box) but positioned relative to the element’s padding box (background-origin: padding-box). This inconsistency can result in unexpected patterns if the element’s border is semi-transparent or dotted/dashed.

A pink and triple rectangle with rounded edges. The colors overlap in a pattern.
.box {   /* semi-transparent border */   border: 20px solid rgba(255, 255, 255, 0.25);    /* background gradient */   background: conic-gradient(     from 45deg at bottom left,     deeppink,     rebeccapurple   ); }

Because of the different initial values, the background gradient in the above image is repeated as a tiled image on all sides under the semi-transparent border. In this case, positioning the background relative to the border box (background-origin: border-box) makes more sense.


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Platform News: Defaulting to Logical CSS, Fugu APIs, Custom Media Queries, and WordPress vs. Italics

Looks like 2021 is the time to start using CSS Logical Properties! Plus, Chrome recently shipped a few APIs that have raised eyebrows, SVG allows us to disable its aspect ratio, WordPress focuses on the accessibility of its typography, and there’s still no update (or progress) on the development of CSS custom media queries.

Let’s jump right into the news…

Logical CSS could soon become the new default

Six years after Mozilla shipped the first bits of CSS Logical Properties in Firefox, this feature is now on a path to full browser support in 2021. The categories of logical properties and values listed in the table below are already supported in Firefox, Chrome, and the latest Safari Preview.

CSS property or value The logical equivalent
margin-top margin-block-start
text-align: right text-align: end
bottom inset-block-end
border-left border-inline-start
(n/a) margin-inline

Logical CSS also introduces a few useful shorthands for tasks that in the past required multiple declarations. For example, margin-inline sets the margin-left and margin-right properties, while inset sets the top, right, bottom and left properties.

/* BEFORE */ main {   margin-left: auto;   margin-right: auto; }  /* AFTER */ main {   margin-inline: auto; }

A website can add support for an RTL (right-to-left) layout by replacing all instances of left and right with their logical counterparts in the site’s CSS code. Switching to logical CSS makes sense for all websites because the user may translate the site to a language that is written right-to-left using a machine translation service. The biggest languages with RTL scripts are Arabic (310 million native speakers), Persian (70 million), and Urdu (70 million).

/* Switch to RTL when Google translates the page to an RTL language */ .translated-rtl {   direction: rtl; }

David Bushell’s personal website now uses logical CSS and relies on Google’s translated-rtl class to toggle the site’s inline base direction. Try translating David’s website to an RTL language in Chrome and compare the RTL layout with the site’s default LTR layout.

Chrome ships three controversial Fugu APIs

Last week Chrome shipped three web APIs for “advanced hardware interactions”: the WebHID and Web Serial APIs on desktop, and Web NFC on Android. All three APIs are part of Google’s capabilities project, also known as Project Fugu, and were developed in W3C community groups (though they’re not web standards).

  • The WebHID API allows web apps to connect to old and uncommon human interface devices that don’t have a compatible device driver for the operating system (e.g., Nintendo’s Wii Remote).
  • The Web Serial API allows web apps to communicate (“byte by byte”) with peripheral devices, such as microcontrollers (e.g., the Arduino DHT11 temperature/humidity sensor) and 3D printers, through an emulated serial connection.
  • Web NFC allows web apps to wirelessly read from and write to NFC tags at short distances (less than 10 cm).

Apple and Mozilla, the developers of the other two major browser engines, are currently opposed to these APIs. Apple has decided to “not yet implement due to fingerprinting, security, and other concerns.” Mozilla’s concerns are summarized on the Mozilla Specification Positions page.

Source: webapicontroversy.com

Stretching SVG with preserveAspectRatio=none

By default, an SVG scales to fit the <svg> element’s content box, while maintaining the aspect ratio defined by the viewBox attribute. In some cases, the author may want to stretch the SVG so that it completely fills the content box on both axes. This can be achieved by setting the preserveAspectRatio attribute to none on the <svg> element.

View demo

Distorting SVG in this manner may seem counterintuitive, but disabling aspect ratio via the preserveAspectRatio=none value can make sense for simple, decorative SVG graphics on a responsive web page:

This value can be useful when you are using a path for a border or to add a little effect on a section (like a diagonal [line]), and you want the path to fill the space.

WordPress tones down the use of italics

An italic font can be used to highlight important words (e.g., the <em> element), titles of creative works (<cite>), technical terms, foreign phrases (<i>), and more. Italics are helpful when used discreetly in this manner, but long sections of italic text are considered an accessibility issue and should be avoided.

Italicized text can be difficult to read for some people with dyslexia or related forms of reading disorders.

Putting the entire help text in italics is not recommended

WordPress 5.7, which was released earlier this week, removed italics on descriptions, help text, labels, error details text, and other places in the WordPress admin to “improve accessibility and readability.”

In related news, WordPress 5.7 also dropped custom web fonts, opting for system fonts instead.

Still no progress on CSS custom media queries

The CSS Media Queries Level 5 module specifies a @custom-media rule for defining custom media queries. This proposed feature was originally added to the CSS spec almost seven years ago (in June 2014) and has since then not been further developed nor received any interest from browser vendors.

@custom-media --narrow-window (max-width: 30em);  @media (--narrow-window) {   /* narrow window styles */ }

A media query used in multiple places can instead be assigned to a custom media query, which can be used everywhere, and editing the media query requires touching only one line of code.

Custom media queries may not ship in browsers for quite some time, but websites can start using this feature today via the official PostCSS plugin (or PostCSS Preset Env) to reduce code repetition and make media queries more readable.

On a related note, there is also the idea of author-defined environment variables, which (unlike custom properties) could be used in media queries, but this potential feature has not yet been fully fleshed out in the CSS spec.

@media (max-width: env(--narrow-window)) {   /* narrow window styles */ }

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Weekly Platform News: Focus Rings, Donut Scope, Ditching em Units, and Global Privacy Control

In this week’s news, Chrome tackles focus rings, we learn how to get “donut” scope, Global Privacy Control gets big-name adoption, it’s time to ditch pixels in media queries, and a snippet that prevents annoying form validation styling.

Chrome will stop displaying focus rings when clicking buttons

Chrome, Edge, and other Chromium-based browsers display a focus indicator (a.k.a. focus ring) when the user clicks or taps a (styled) button. For comparison, Safari and Firefox don’t display a focus indicator when a button is clicked or tapped, but do only when the button is focused via the keyboard.

The focus ring will stay on the button until the user clicks somewhere else on the page.

Some developers find this behavior annoying and are using various workarounds to prevent the focus ring from appearing when a button is clicked or tapped. For example, the popular what-input library continuously tracks the user’s input method (mouse, keyboard or touch), allowing the page to suppress focus rings specifically for mouse clicks.

[data-whatintent="mouse"] :focus {   outline: none; }

A more recent workaround was enabled by the addition of the CSS :focus-visible pseudo-class to Chromium a few months ago. In the current version of Chrome, clicking or tapping a button invokes the button’s :focus state but not its :focus-visible state. that way, the page can use a suitable selector to suppress focus rings for clicks and taps without affecting keyboard users.

:focus:not(:focus-visible) {   outline: none; }

Fortunately, these workarounds will soon become unnecessary. Chromium’s user agent stylesheet recently switched from :focus to :focus-visible, and as a result of this change, button clicks and taps no longer invoke focus rings. The new behavior will first ship in Chrome 90 next month.

The enhanced CSS :not() selector enables “donut scope”

I recently wrote about the A:not(B *) selector pattern that allows authors to select all A elements that are not descendants of a B element. This pattern can be expanded to A B:not(C *) to create a “donut scope.”

For example, the selector article p:not(blockquote *) matches all <p> elements that are descendants of an <article> element but not descendants of a <blockquote> element. In other words, it selects all paragraphs in an article except the ones that are in a block quotation.

The donut shape that gives this scope its name

The New York Times now honors Global Privacy Control

Announced last October, Global Privacy Control (GPC) is a new privacy signal for the web that is designed to be legally enforceable. Essentially, it’s an HTTP Sec-GPC: 1 request header that tells websites that the user does not want their personal data to be shared or sold.

The DuckDuckGo Privacy Essentials extension enables GPC by default in the browser

The New York Times has become the first major publisher to honor GPC. A number of other publishers, including The Washington Post and Automattic (WordPress.com), have committed to honoring it “this coming quarter.”

From NYT’s privacy page:

Does The Times support the Global Privacy Control (GPC)?

Yes. When we detect a GPC signal from a reader’s browser where GDPR, CCPA or a similar privacy law applies, we stop sharing the reader’s personal data online with other companies (except with our service providers).

The case for em-based media queries

Some browsers allow the user to increase the default font size in the browser’s settings. Unfortunately, this user preference has no effect on websites that set their font sizes in pixels (e.g., font-size: 20px). In part for this reason, some websites (including CSS-Tricks) instead use font-relative units, such as em and rem, which do respond to the user’s font size preference.

Ideally, a website that uses font-relative units for font-size should also use em values in media queries (e.g., min-width: 80em instead of min-width: 1280px). Otherwise, the site’s responsive layout may not always work as expected.

For example, CSS-Tricks switches from a two-column to a one-column layout on narrow viewports to prevent the article’s lines from becoming too short. However, if the user increases the default font size in the browser to 24px, the text on the page will become larger (as it should) but the page layout will not change, resulting in extremely short lines at certain viewport widths.

If you’d like to try out em-based media queries on your website, there is a PostCSS plugin that automatically converts min-width, max-width, min-height, and max-height media queries from px to em.

(via Nick Gard)

A new push to bring CSS :user-invalid to browsers

In 2017, Peter-Paul Koch published a series of three articles about native form validation on the web. Part 1 points out the problems with the widely supported CSS :invalid pseudo-class:

  • The validity of <input> elements is re-evaluated on every key stroke, so a form field can become :invalid while the user is still typing the value.
  • If a form field is required (<input required>), it will become :invalid immediately on page load.

Both of these behaviors are potentially confusing (and annoying), so websites cannot rely solely on the :invalid selector to indicate that a value entered by the user is not valid. However, there is the option to combine :invalid with :not(:focus) and even :not(:placeholder-shown) to ensure that the page’s “invalid” styles do not apply to the <input> until the user has finished entering the value and moved focus to another element.

The CSS Selectors module defines a :user-invalid pseudo-class that avoids the problems of :invalid by only matching an <input> “after the user has significantly interacted with it.”

Firefox already supports this functionality via the :-moz-ui-invalid pseudo-class (see it in action). Mozilla now intends to un-prefix this pseudo-class and ship it under the standard :user-invalid name. There are still no signals from other browser vendors, but the Chromium and WebKit bugs for this feature have been filed.


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Weekly Platform News: Reduced Motion, CORS, WhiteHouse.gov, popups, and 100vw

In this week’s roundup, we highlight a proposal for a new <popup> element, check the use of prefers-reduced-motion on award-winning sites, learn how to opt into cross-origin isolation, see how WhiteHouse.gov approaches accessibility, and warn the dangers of 100vh.

Let’s get into the news!

The new HTML <popup> element is in development

On January 21, Melanie Richards from the Microsoft Edge web platform team posted an explainer for a proposed HTML <popup> element (the name is not final). A few hours later, Mason Freed from Google announced an intent to prototype this element in the Blink browser engine. Work on the implementation is taking place in Chromium issue #1168738.

A popup is a temporary (transient) and “light-dismissable” UI element that is displayed on the the “top layer” of all other elements. The goal for the <popup> element is to be fully stylable and accessible by default. A <popup> can be anchored to an activating element, such as a button, but it can also be a standalone element that is displayed on page load (e.g., a teaching UI).

Two use cases showing a white action menu with four gray menu links below a blue menu button, and another example of a blog button with a large dark blue tooltip beneath it with two paragraphs of text in white.

A <popup> is automatically hidden when the user presses the Esc key or moves focus to a different element (this is called a light dismissal). Unlike the <dialog> element, only one <popup> can be shown at a time, and unlike the deprecated <menu> element, a <popup> can contain arbitrary content, including interactive elements:

We imagine <popup> as being useful for various different types of popover UI. We’ve chosen to use an action menu as a primary example, but folks use popup-esque patterns for many different types of content.

Award-winning websites should honor the “reduce motion” preference

Earlier this week, AWWWARDS announced the winners of their annual awards for the best websites of 2020. The following websites were awarded:

All these websites are highly dynamic and show full-screen motion on load and during scroll. Unfortunately, such animations can cause dizziness and nausea in people with vestibular disorders. Websites are therefore advised to reduce or turn off non-essential animations via the prefers-reduced-motion media query, which evaluates to true for people who have expressed their preference for reduced motion (e.g., the “Reduce motion” option on Apple’s platforms). None of the winning websites do this.

/* (code from animal-crossing.com) */ @media (prefers-reduced-motion: reduce) {   .main-header__scene {     animation: none;   } }

An example of a website that does this correctly is the official site of last year’s Animal Crossing game. Not only does the website honor the user’s preference via prefers-reduced-motion, but it also provides its own “Reduce motion” toggle button at the very top of the page.

Screenshot of the animal crossing game website that is bright with a solid green header above a gold ribbon that displays menu items. Below is the main banner showing a still of the animated game with a wooden welcome to Animal Crossing sign in the foreground.

(via Eric Bailey)

Websites can now opt into cross-origin isolation

Cross-origin isolation is part of a “long-term security improvement.” Websites can opt into cross-origin isolation by adding the following two HTTP response headers, which are already supported in Chrome and Firefox:

Cross-Origin-Embedder-Policy: require-corp Cross-Origin-Opener-Policy: same-origin

A cross-origin-isolated page relinquishes its ability to load content from other origins without their explicit opt-in (via CORS headers), and in return, the page gains access to some powerful APIs, such as SharedArrayBuffer.

if (crossOriginIsolated) {   // post SharedArrayBuffer } else {   // do something else }

The White House recommits to accessibility

The new WhiteHouse.gov website of the Biden administration was built from scratch in just six weeks with accessibility as a top priority (“accessibility was top of mind”). Microsoft’s chief accessibility officer reviewed the site and gave it the thumbs up.

The website’s accessibility statement (linked from the site’s footer) declares a “commitment to accessibility” and directly references the latest version of the Web Content Accessibility Guidelines, WCAG 2.1 (2018). This is notable because federal agencies in the USA are only required to comply with WCAG 2.0 (2008).

The Web Content Accessibility Guidelines are the most widely accepted standards for internet accessibility. … By referencing WCAG 2.1 (the latest version of the guidelines), the Biden administration may be indicating a broader acceptance of the WCAG model.

The CSS 100vw value can cause a useless horizontal scrollbar

On Windows, when a web page has a vertical scrollbar, that scrollbar consumes space and reduces the width of the page’s <html> element; this is called a classic scrollbar. The same is not the case on macOS, which uses overlay scrollbars instead of classic scrollbars; a vertical overlay scrollbar does not affect the width of the <html> element.

macOS users can switch from overlay scrollbars to classic scrollbars by setting “Show scroll bars” to ”Always” in System preferences > General.

The CSS length value 100vw is equal to the width of the <html> element. However, if a classic vertical scrollbar is added to the page, the <html> element becomes narrower (as explained above), but 100vw stays the same. In other words, 100vw is wider than the page when a classic vertical scrollbar is present.

This can be a problem for web developers on macOS who use 100vw but are unaware of its peculiarity. For example, a website might set width: 100vw on its article header to make it full-width, but this will cause a useless horizontal scrollbar on Windows that some of the site’s visitors may find annoying.

Screenshot of an article on a white background with a large black post title, post date and red tag links above a paragraph of black text. A scrollbar is displayed on the right with two large red arrows illustrating the page width, which is larger than the 100 viewport width unit.

Web developers on macOS can switch to classic scrollbars to make sure that overflow bugs caused by 100vw don’t slip under their radar. In the meantime, I have asked the CSS Working Group for comment.


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Weekly Platform News: WebKit autofill, Using Cursor Pointer, Delaying Autoplay Videos

In this week’s roundup, WebKit’s prefixed autofill becomes a standard, the pointer cursor is for more than just links, and browsers are jumping on board to delay videos set to autoplay until they’re in view… plus more! Let’s jump right into it.

CSS ::-webkit-autofill has become a standard feature

Chrome, Safari, and pretty much every other modern web browser except Firefox (more on that later) have supported the CSS :-webkit-autofill pseudo-class for many years. This selector matches form fields that have been autofilled by the browser. Websites can use this feature to style autofilled fields in CSS (with some limitations) and detect such fields in JavaScript.

let autofilled = document.querySelectorAll(":-webkit-autofill");

There currently does not exist a standard autocomplete or autofill event that would fire when the browser autofills a form field, but you can listen to the input event on the web form and then check if any of its fields match the :-webkit-autofill selector.

The HTML Standard has now standardized this feature by adding :autofill (and :-webkit-autofill as an alias) to the list of pseudo-classes that match HTML elements. This pseudo-class will also be added to the CSS Selectors module.

The :autofill and :-webkit-autofill pseudo-classes must match <input> elements that have been autofilled by the user agent. These pseudo-classes must stop matching if the user edits the autofilled field.

Following standardization, both pseudo-classes have been implemented in Firefox and are expected to ship in Firefox 86 later this month.

In the article “Let’s Bring Spacer GIFs Back!” Josh W. Comeau argues for using a “spacer” <span> element instead of a simple CSS margin to define the spacing between the icon and text of a button component.

In our home-button example, should the margin go on the back-arrow, or the text? It doesn’t feel to me like either element should “own” the space. It’s a distinct layout concern.

CSS Grid is an alternative to such spacer elements. For example, the “Link to issue” link in CSS-Tricks’s newsletter section contains two non-breaking spaces (&nbsp;) to increase the spacing between the emoji character and text, but the link could instead be turned into a simple grid layout to gain finer control over the spacing via the gap property.

The CSS Basic User Interface module defines the CSS cursor property, which allows websites to change the type of cursor that is displayed when the user hovers specific elements. The specification has the following to say about the property’s pointer value:

The cursor is a pointer that indicates a link. … User agents must apply cursor: pointer to hyperlinks. … Authors should use pointer on links and may use on other interactive elements.

Accordingly, browsers display the pointer cursor (rendered as a hand) on links and the default cursor (rendered as an arrow) on buttons. However, most websites (including Wikipedia) don’t agree with this default style and apply cursor: pointer to other interactive elements, such as buttons and checkboxes, as well.

Another interactive element for which it makes sense to use the pointer cursor is the <summary> element (the “toggle button” for opening and closing the parent <details> element).

Browsers delay autoplay until the video comes into view

Compared to modern video formats, animated GIF images are up to “twice as expensive in energy use.” For that reason, browsers have relaxed their video autoplay policies (some time ago) to encourage websites to switch from GIFs to silent or muted videos.

<!-- a basic re-implementation of a GIF using <video> --> <video autoplay loop muted playsinline src="meme.mp4"></video>

If you’re using <video muted autoplay>, don’t worry about pausing such videos when they’re no longer visible in the viewport (e.g., using an Intersection Observer). All major browsers (except Firefox) already perform this optimization by default:

<video autoplay> elements will only begin playing when visible on-screen such as when they are scrolled into the viewport, made visible through CSS, and inserted into the DOM.

(via Zach Leatherman)

Chrome introduces three new @font-face descriptors

Different browsers and operating systems sometimes use different font metrics even when rendering the same font. These differences affect the vertical position of text, which is especially noticeable on large headings.

Similarly, the different font metrics of a web font and its fallback font can cause a layout shift when the fonts are swapped during page load.

To help websites avoid layout shift and create interoperable text layouts, Chrome recently added the following three new CSS @font-face descriptors for overriding the font’s default metrics:

  • ascent-override (ascent is the height above the baseline)
  • descent-override (descent is the depth below the baseline)
  • line-gap-override
@font-face {   font-family: Roboto;   /* Merriweather Sans has 125.875px ascent     * and 35px descent at 128px font size.    */   ascent-override: calc(125.875 / 128 * 100%);   descent-override: calc(35 / 128 * 100%);   src: local(Roboto-Regular); }

The following video shows how overriding the ascent and descent metrics of the fallback font (Roboto) to match the same metrics of the web font (Merriweather Sans) can avoid layout shift when swapping between these two fonts.


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Weekly Platform News: The :not() pseudo-class, Video Media Queries, clip-path: path() Support

Hey, we’re back with weekly updates about the browser landscape from Šime Vidas.

In this week’s update, the CSS :not pseudo class can accept complex selectors, how to disable smooth scrolling when using “Find on page…” in Chrome, Safari’s support for there media attribute on <video> elements, and the long-awaited debut of the path() function for the CSS clip-path property.

Let’s jump into the news…

The enhanced :not() pseudo-class enables new kinds of powerful selectors

After a years-long wait, the enhanced :not() pseudo-class has finally shipped in Chrome and Firefox, and is now supported in all major browser engines. This new version of :not() accepts complex selectors and even entire selector lists.

For example, you can now select all <p> elements that are not contained within an <article> element.

/* select all <p>s that are descendants of <article> */ article p { }  /* NEW! */ /* select all <p>s that are not descendants of <article> */ p:not(article *) { }

In another example, you may want to select the first list item that does not have the hidden attribute (or any other attribute, for that matter). The best selector for this task would be :nth-child(1 of :not([hidden])), but the of notation is still only supported in Safari. Luckily, this unsupported selector can now be re-written using only the enhanced :not() pseudo-class.

/* select all non-hidden elements that are not preceded by a non-hidden sibling (i.e., select the first non-hidden child */ :not([hidden]):not(:not([hidden]) ~ :not([hidden])) { }

The HTTP Refresh header can be an accessibility issue

The HTTP Refresh header (and equivalent HTML <meta> tag) is a very old and widely supported non-standard feature that instructs the browser to automatically and periodically reload the page after a given amount of time.

<!-- refresh page after 60 seconds --> <meta http-equiv="refresh" content="60">

According to Google’s data, the <meta http-equiv="refresh"> tag is used by a whopping 2.8% of page loads in Chrome (down from 4% a year ago). All these websites risk failing several success criteria of the Web Content Accessibility Guidelines (WCAG):

If the time interval is too short, and there is no way to turn auto-refresh off, people who are blind will not have enough time to make their screen readers read the page before the page refreshes unexpectedly and causes the screen reader to begin reading at the top.

However, WCAG does allow using the <meta http-equiv="refresh"> tag specifically with the value 0 to perform a client-side redirect in the case that the author does not control the server and hence cannot perform a proper HTTP redirect.

(via Stefan Judis)

How to disable smooth scrolling for the “Find on page…” feature in Chrome

CSS scroll-behavior: smooth is supported in Chrome and Firefox. When this declaration is set on the <html> element, the browser scrolls the page “in a smooth fashion.” This applies to navigations, the standard scrolling APIs (e.g., window.scrollTo({ top: 0 })), and scroll snapping operations (CSS Scroll Snap).

Unfortunately, Chrome erroneously keeps smooth scrolling enabled even when the user performs a text search on the page (“Find on page…” feature). Some people find this annoying. Until that is fixed, you can use Christian Schaefer’s clever CSS workaround that effectively disables smooth scrolling for the “Find on page…” feature only.

@keyframes smoothscroll1 {   from,   to {     scroll-behavior: smooth;   } }  @keyframes smoothscroll2 {   from,   to {     scroll-behavior: smooth;   } }  html {   animation: smoothscroll1 1s; }  html:focus-within {   animation-name: smoothscroll2;   scroll-behavior: smooth; }

In the following demo, notice how clicking the links scrolls the page smoothly while searching for the words “top” and “bottom” scrolls the page instantly.

Safari still supports the media attribute on video sources

With the HTML <video> element, it is possible to declare multiple video sources of different MIME types and encodings. This allows websites to use more modern and efficient video formats in supporting browsers, while providing a fallback for other browsers.

<video>   <source src="/flower.webm" type="video/webm">   <source src="/flower.mp4" type="video/mp4"> </video>

In the past, browsers also supported the media attribute on video sources. For example, a web page could load a higher-resolution video if the user’s viewport exceeded a certain size.

<video>   <source media="(min-width: 1200px)" src="/large.mp4" type="video/mp4">   <source src="/small.mp4" type="video/mp4"> </video>

The above syntax is in fact still supported in Safari today, but it was removed from other browsers around 2014 because it was not considered a good feature:

It is not appropriate for choosing between low resolution and high resolution because the environment can change (e.g., the user might fullscreen the video after it has begun loading and want high resolution). Also, bandwidth is not available in media queries, but even if it was, the user agent is in a better position to determine what is appropriate than the author.

Scott Jehl (Filament Group) argues that the removal of this feature was a mistake and that websites should be able to deliver responsive video sources using <video> alone.

For every video we embed in HTML, we’re stuck with the choice of serving source files that are potentially too large or small for many users’ devices … or resorting to more complicated server-side or scripted or third-party solutions to deliver a correct size.

Scott has written a proposal for the reintroduction of media in video <source> elements and is welcoming feedback.

The CSS clip-path: path() function ships in Chrome

It wasn’t mentioned in the latest “New in Chrome 88” article, but Chrome just shipped the path() function for the CSS clip-path property, which means that this feature is now supported in all three major browser engines (Safari, Firefox, and Chrome).

The path() function is defined in the CSS Shapes module, and it accepts an SVG path string. Chris calls this the ultimate syntax for the clip-path property because it can clip an element with “literally any shape.” For example, here’s a photo clipped with a heart shape:


The post Weekly Platform News: The :not() pseudo-class, Video Media Queries, clip-path: path() Support appeared first on CSS-Tricks.

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Jamstack News!

I totally forgot that the Jamstack Conf was this week but thankfully they’ve already published the talks on the Jamstack YouTube channel. I’m really looking forward to sitting down with these over a coffee while I also check out Netlify’s other big release today: Build Plugins.

These are plugins that run whenever your site is building. One example is the A11y plugin that will fail a build if accessibility failures are detected. Another minifies HTML and there’s even one that inlines critical CSS. What’s exciting is that these build plugins are kinda making complex Gulp/Grunt environments the stuff of legend. Instead of going through the hassle of config stuff, build plugins let Netlify figure it all out for you. And that’s pretty neat.

Also, our very own Sarah Drasner wrote just about how to create your first Netlify Build Plugin. So, if you have an idea for something that you could share with the community, then that may be the best place to start.

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Weekly Platform News: Strict Tracking Protection, Dark Web Pages, Periodic Background Sync

In this week’s news: Firefox gets strict, Opera goes to the dark side, and Chrome plans to let web apps run in the background.

Let’s get into the news.

Firefox for Android will block tracking content

Mozilla has announced that the upcoming revamped Firefox for Android (currently available in a test version under the name “Firefox Preview”) will include strict tracking protection by default.

On the phone or tablet, most users care much more about performance and blocking of annoyances compared to desktop. Users are more forgiving when a site doesn’t load exactly like it’s meant to. So we decided that while Firefox for desktop’s default mode is “Standard,” Firefox Preview will use “Strict” mode.

Strict tracking protection additionally blocks “tracking content”: ads, videos, and other content with tracking code.

(via Mozilla)

Opera adds option that renders all websites in dark mode

Opera for Android has added a “Dark web pages” option that renders all websites in dark mode. If a website does not provide dark mode styles (via the CSS prefers-color-scheme media feature), Opera applies its own “clever CSS changes” to render the site in dark mode regardless.

(via Stefan Stjernelund)

Periodic Background Sync is coming to Chrome

Google intends to ship Periodic Background Sync in the next version of Chrome (early next year). This feature will enable installed web apps to run background tasks at periodic intervals with network connectivity.

Chrome’s implementation restricts the API to installed web apps. Chrome grants the permission on behalf of the user for any installed web app. The API is not available outside of installed PWAs.

Apple and Mozilla are currently opposed to this API. At Mozilla, there are opinions that the feature is “harmful in its current state,” while Apple states multiple privacy and security risks.

(via Mugdha Lakhani)

More news…

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