Webmasters Gallery

There is a code snippet that I see all the time when the media query prefers-reduced-motion is talked about. Here it is:

@media (prefers-reduced-motion: reduce) {
  * {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}

This is CSS that attempts to obliterate any motion on a website under the condition that the user has specified a preference for reduced motion in the accessibility preferences of their operating system.

Why prefers-reduced-motion matters

The reason this setting exists is that on-screen movement is an accessibility concern. Here’s Eric Bailey:

Vestibular disorders can cause your vestibular system to struggle to make sense of what is happening, resulting in loss of balance and vertigo, migraines, nausea, and hearing loss. Anyone who has spun around too quickly is familiar with a confused vestibular system.

Vestibular disorders can be caused by both genetic and environmental factors. It’s part of the larger spectrum of conditions that make up accessibility concerns and it affects more than 70 million people.

Here he is again in a follow-up article:

If you have a vestibular disorder or have certain kinds of migraine or seizure triggers, navigating the web can be a lot like walking through a minefield — you’re perpetually one click away from activating an unannounced animation. And that’s just for casual browsing.

Reduced motion vs. nuked motion

Knowing this, the temptation might be high to go nuclear on the motion and wipe it out entirely when a user has specified a reduced motion preference. The trouble with that is — to quote Eric again — “animation isn’t unnecessary.” Some of it might be, but animation can also help accessibility. For example, a “transitional interface” (e.g. a list that animates an opening for a new item to slide into it) can be very helpful:

Animation can be a great tool to help combat some forms of cognitive disability by using it to break down complicated concepts, or communicate the relationship between seemingly disparate objects. Val Head’s article on A List Apart highlights some other very well-researched benefits, including helping to increase problem-solving ability, recall, and skill acquisition, as well as reducing cognitive load and your susceptibility to change blindness.

In this case, you would lose the helpful contextual movement if you just nuked it all. You just might want to take a different approach when in a prefers-reduced-motion scenario. Perhaps less, slower, or removed motion while leaning harder on color and fading transitions.

Ban Nadel recently wrote “Applying Multiple Animation @keyframes To Support Prefers-Reduced-Motion In CSS” and covered a similar example. A modal entrance animation uses both a fade-in and scale-in effect by default. Then, in a prefers-reduced-motion scenario, it uses the fade-in but not the scaling. The scaling causes movement in a way the fading doesn’t.

/* 
  By default, we'll use the REDUCED MOTION version of the animation.
*/
@keyframes modal-enter {
  from {
    opacity: 0 ;
  }
  to {
    opacity: 1 ;
  }
}

/*
  Then, if the user has NO PREFERENCE for motion, we can OVERRIDE the
  animation definition to include both the motion and non-motion properties.
*/
@media ( prefers-reduced-motion: no-preference ) {
  @keyframes modal-enter {
    from {
      opacity: 0 ;
      transform: scale(0.7) ;
    }
    to {
      opacity: 1 ;
      transform: scale(1.0) ;
    }
  }
}

See the GIF demo on Ben’s site if you’d like to see a quick comparison.

I like how this style of approach is think about the problem and come up with a reduced motion solution, rather than screw it all, no movement period!!

But not all motion is driven by CSS

While we’re on the topic of that screw-all-motion CSS snippet, note that it’s only effective at doing what it sets out to do on sites where all the movement is entirely CSS-driven. If you’re using JavaScript-powered animations beware that this nuclear snippet might… well here’s Josh Comeau:

If your animations are entirely driven by CSS, this works great… But I’ve had weird issues when running animations in JS. Specifically, I’ve seen this reset have the opposite effect, and make animations super fast and dizzying.

That’s right: It might do quite literally the opposite of what you are trying to do.

No Motion Isn’t Always prefers-reduced-motion originally published on CSS-Tricks. You should get the newsletter and become a supporter.