Unlock the Power of CSS: Understanding Specificity
As a CSS developer, you know how crucial it is to grasp the fundamental concepts of cascade, inheritance, and specificity. Among these, specificity plays a vital role in resolving conflicts when multiple selectors with different style rules target the same element. In this article, we’ll dive into the world of CSS specificity, exploring its hierarchy, calculation, and exceptions.
What is CSS Specificity?
When an element has multiple selectors with conflicting style rules, the browser uses specificity scores to determine which style should be applied. The selector with the highest specificity score wins, and its style rules are applied to the element. Specificity only comes into play when multiple declarations target the same element.
The Specificity Hierarchy
The specificity hierarchy is a four-part system that ranks selectors based on their importance. From highest to lowest, the hierarchy consists of:
- Inline Style Selectors: With a specificity score of 1000, these selectors take precedence over others.
- ID Selectors: Scoring 100, ID selectors come next in the hierarchy.
- Class, Pseudo-Class, and Attribute Selectors: With a score of 10, these selectors follow ID selectors.
- Element and Pseudo-Element Selectors: The lowest in the hierarchy, these selectors score 1.
Calculating Specificity
To calculate the specificity score for multiple selectors, you need to sum up the individual selector specificities. Let’s consider an example:
| Selector | Inline Style | ID | Class | Element |
| — | — | — | — | — |
| #payment | 0 | 1 | 0 | 0 |
| .modal | 0 | 0 | 1 | 0 |
| div | 0 | 0 | 0 | 1 |
In this example, the total specificity score for each selector is 100, 10, and 1, respectively.
Multiple Classes vs. ID Selectors
What happens when multiple classes compete with a single ID selector? Regardless of the number of classes, the ID selector will always win due to its higher specificity score.
The!important Rule Exception
When an !important rule is used in a style declaration, it takes precedence over other declarations. However, relying on !important can lead to debugging issues and should be avoided.
Proximity Ignorance
Proximity ignorance means that the nesting level of a selector does not affect its specificity. The CSS cascade rule comes into play only when specificity is equal.
Inherited Styles vs. Directly Targeted Elements
Directly targeted elements always take precedence over inherited styles, regardless of specificity.
By grasping the concept of CSS specificity, you’ll be able to quickly identify which selector’s style rules should be applied to a particular element, and debug development bugs more efficiently.