When Should You Use the CSS !important Rule?

William Le

The !important rule in CSS gives you the ability to override styles, but is this power too much for a lone software developer? Read this article to find out what it is, and when it’s a good idea to use it!

The !important rule is special because it has the ability to override the natural cascade of CSS styles.

Consider the following HTML/CSS code… What color do you think the text will be?

<div>
  <h1 id="title">Sir Chompsalot</h1>
</div>
div h1 {
  color: blue !important;
}

div h1 {
  color: green;
}

Normally, if we have two CSS rules with identical specificity the latter rule would win. In this case, the earlier CSS rule beats any latter rules simply because it has the powerful !important rule.

The text is blue!

Using the same HTML markup, what if we got even more specific by targeting the body tag and h1#title?

div h1 {
  color: blue !important;
}

body div h1#title {
  color: green;
}

Will this have the ability to override the !important rule?

Nope! Wow, the !important rule is almost too powerful for its own good.


💪🤖💪

Since !important contradicts the expected behavior of CSS, it’s generally recommended to avoid using it. If you rely on !important too often it can cause a lot of unexpected behavior down the road, and new developers will have a hard time debugging their CSS. Why isn’t this text changing color! 😂

Does this mean you should never use it?

Occasions to Use !important

As time has passed since !important was introduced to CSS there seems to be some consensus that it’s really only useful for a single job: dealing with foreign CSS.

Foreign CSS is essentially any CSS that you don’t have direct ability to change or improve yourself. Two practical instances of foreign CSS are:

  • JavaScript Frameworks & External Libraries: This applies to popular libraries like Bootstrap, or Normalize. Since you can’t edit their CSS styles directly, sometimes your only option is override their CSS with your own !important rules.
  • User Styles: This used to be very popular years ago. User Styles provides a way for you to create your own CSS to inject on websites owned by other people/companies. For example, this dark theme for instagram.com

Since foreign CSS can’t be changed by you (unless you take a job at Instagram to rectify their serious lack of a dark mode), the !important rule is really your only, and best option.

The folks at Mozilla Developer Network and CSS-Tricks seem to agree that !important is really only useful for dealing with foreign CSS

Conclusion

If you are really tempted to use !important, try reflecting on architectural decisions that you can make. Not just your CSS either. This could mean adding new HTML tags, or applying new classes/ids. Engaging in this architecture-centric practice results in high quality code that’s a joy to maintain! 🤓

Have you found other appropriate uses for !important? Tweet us at @alligatorio and share it with us!

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