CSS & a11y: When hiding with opacity, also set visibility:hidden (transitions supported)

Elements can be hidden and shown by toggling the display property. However, this is not animatable, so we often turn to opacity. At opacity: 0, the element is hidden, and with a nice transition on that property, it can be faded in and out smoothly.

Yet, opacity only hides visually, not technically: the element is still focusable and visible to screen readers. So, how can we fade an element while maintaining accessibility?

Enter visibility Show archive.org snapshot . It also hides elements, but differently from display – and it can be transitioned Show archive.org snapshot . It will not fade by itself (still toggles), but it is kind enough to always be visible during transition. This makes it a perfect complement for opacity. Just transition both of them:

Copyopacity: 0
visibility: hidden
transition: all 100ms

&.-visible
  opacity: 1
  visibility: visible

When fading in, visibility will immediately be set to visible, allowing the opacity transition to be shown. When fading out, visibility will remain visible until the opacity transition is over. Thanks to visibility, the hidden element is truly hidden and neither focusable nor visible to screen readers.

Alternatives

If you're starting your transition from JavaScript, you can give the element the [inert] Show archive.org snapshot attribute. This will make the browser ignore input events and prevent focus.

In the future we will be able to transition to display: none Show archive.org snapshot by using the transition-behavior: allow-discrete property. This will delay the display change until the transition ends. This is supported in all browsers except Firefox Show archive.org snapshot .