Responsive, semantic images with CSS

#webdev #css #a11y #tip

CSS tip: object-fit your images.

To have an image that doesn't try to stretch to its width/height the classic CSS is as follows:

.thumbnail {
  width: 50px;
  height: 50px;
  background-size: cover;
  background-position: center;
}

With this associated HTML (inline styles… 👎):

<div
  class="thumbnail"
  style="background-image: url('some-url');"
>
</div>

We can do:

.thumbnail {
  width: 50px;
  height: 50px;
  object-fit: cover;
  object-position: center;
}

With the following HTML:

<img
  class="thumbnail"
  alt="My thumbnail"
  src="some-url">

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Why is this cool?

One word: accessibility.
Two words: semantic markup.
Many words, with the div + background-image solution:
1. if the URL turned out to be broken, it would show empty space, with the img + object-fit one, it shows the good old “broken image because of URL” fallback (or alt attribute value).
2. An img tag is more accessible since we can have alt
3. Typing src="my-url" is just less characters than style="background-image: url('my-url')".

Warning: this might not work on older browsers, it does, however gracefully degrade (the image will just be stretched), it won't mess up the layout though.

unsplash-logoNate Bell

Top comments (5)

Cristian N • Jul 6 '18

I haven't really worked on enterprise apps/sites but I can tell you I have ignored ie9 for years for all my css work. And what's more, I am beginning to think that ignoring ie11 might be a good idea as well. Looking at caniuse, I don't think it's a good idea to waste time on making an app/site compatible with old, very low usage versions of browsers.

Hugo Di Francesco • Jul 6 '18

object fit degrades ok anyways, the image will be stretched, but I remember the days when background-image would result in a blank block in legacy browsers of the day (and you would have to polyfill that)