How Does `!important` Interact with CSS Specificity?

The Complexity of !important and CSS Specificity

In the realm of CSS, the relationship between the "!important" rule and selector specificity can be a source of ambiguity. While CSS specificity revolves around selectors, !important influences the overall cascade behavior of rules declared in a stylesheet.

Specificity and Cascade

Selector specificity determines which CSS rule overrides another in scenarios where multiple rules apply to the same element. !important, on the other hand, exists within declarations and affects the cascade. It overrides any rules with lower specificity, but it does not affect specificity itself.

How !important Overrides

Imagine !important as a "spades card" in a game. It trumps all specificity points, meaning that a rule with an !important declaration will always override any non-important rule, regardless of the selector's specificity.

Multiple !important Declarations

When you have more than one !important declaration in a single rule for the same element, the later-declared rule will win. This is because the cascade favors later-defined rules.

Specificity vs. !important in Different Stylesheets

When rules with conflicting declarations are declared in different stylesheets, such as external and inline styles, !important follows the cascading order. If both declarations are important, the more specific selector will determine which rule overrides the other.

Case Studies

Consider the following HTML:

<span>

If you apply the following rules:

#id {
  color: red;
}

.class {
  color: blue !important;
}

The "!important" declaration in the ".class" rule will always override the "#id" rule because of its higher importance.

Now, if you replace the non-important rule with another !important rule:

#id {
  color: red !important;
}

In this scenario, the "#id" rule wins because its selector has a higher specificity.

Conclusion

Understanding the interplay between !important and CSS specificity is crucial for managing styles effectively. Remember, !important influences the cascade and overrides specificity, but it does not affect selector specificity itself. By carefully considering the importance and specificity of your rules, you can achieve the desired visual outcomes in your CSS designs.

The above is the detailed content of How Does `!important` Interact with CSS Specificity?. For more information, please follow other related articles on the PHP Chinese website!