Using !important in CSS is a mandatory means to override style priority issues, but should be used with caution. The core rule is: !important lets the specified style skip normal cascade logic and obtain the highest priority unless the same attribute is encountered and the same mark !important rules are still determined by the selector characteristics and order. For example, p {color:red !important} will still display red text even when facing higher-character ID selectors such as #special-paragraph {color:blue}. Applicable scenarios include: 1. Overwrite inline styles in third-party content; 2. Quickly test style effects during development and debugging; 3. Ensure that the modifications take effect in user-defined styles or browser extensions. However, abuse!important can lead to maintenance difficulties, disrupt the casing mechanism and develop bad coding habits. Safer alternatives include: 1. Improve selector specificity (such as using .parent .child instead of .child); 2. Adjust the order of style sheets to make the key rules backwards; 3. Use tool-class priority framework to reduce conflicts; 4. Increase specificity by repeating class names (such as .button.button{}); 5. Organize CSS structures layered to achieve style control naturally. Therefore, !important should be used as a temporary emergency solution rather than a long-term solution.

The !important rule in CSS is a way to override the natural cascade and specificity of styles. In short, it tells the browser that this style should take priority over others, even if there are more specific selectors or later rules.

It can be useful in some situations, but it's generally best to avoid it unless absolutely necessary — because once you start using it, you may find yourself needing to use it again and again to keep things working.

How !important affects CSS specification

Normally, CSS resolves conflicts based on selector specification and source order. More specific selectors win, and if two have equal specification, the one that comes last wins.

Adding !important to a CSS declaration essentially jumps to the top of that hierarchy. It makes that property and value ignore the usual rules and take precedence — unless another !important rule for the same property exists on the same element, in which case the one with higher specification (or later in the stylesheet) will win.

For example:

 p {
  color: red !important;
}

#special-paragraph {
  color: blue;
}

Even though the ID selector #special-paragraph has much higher specification than the p selector, the paragraph will still be red — because of !important .

When it might make sense to use !important

There are a few scenarios where using !important can be justified — though they're relatively rare.

• Overriding inline styles
  If you don't control the HTML (like in third-party widgets or CMS-generated content), and you need to override an inline style, !important might be your only option.

• Quick fixes during development or debugging
  Sometimes when you're trying to test how a certain style looks, adding !important temporarily can help bypass complex specific issues without rewriting large chunks of CSS.

• In user stylesheets or browser extensions
  If you're writing custom styles to override website behavior (like dark mode tweaks), !important helps ensure your changes stick.

Still, these uses should be limited. If you find yourself using !important often, it's a sign your CSS architecture might need rethinking.

Why you should usually avoid !important

Using !important too often leads to problems:

• Harder to maintain and debug
  Once you have multiple !important rules, figuring out why something is styled a certain way becomes confusing.

• Breaks the cascade
  The whole point of CSS is that styles build on each other logically. !important disrupts that flow.

• Encourages poor CSS practices
  It becomes a shortcut instead of addressing the real issue — like improving selector specificity or organizing your CSS better.

Instead of reaching for !important , try:

• Using a more specific selector (eg, .parent .child instead of just .child )
• Reordering your stylesheets so important rules come later
• Using utility-first frameworks like Tailwind, which reduce specific conflicts

A safer alternative: Use specificity wisely

Rather than forcing overrides with !important , think about how to structure your CSS so it naturally applies the right styles.

One common trick is to repeat class names to increase specificity:

 /* Low specific */
.button {}

/* Higher specificity */
.button.button {}

This method lets you override base styles without breaking the cascade.

Another approach is organizing your CSS into layers — like base styles, component styles, and utility styles — where each layer builds on the previous one. That way, you rarely need to force overrides.

So while !important isn't evil, it's definitely a tool to use sparingly. Think of it as a temporary bandage, not a permanent solution.

Basically that's it.

The above is the detailed content of What is the significance of the !important rule in CSS, and when (if ever) should it be used?. For more information, please follow other related articles on the PHP Chinese website!