Understanding the CSS !important Rule

Understanding the CSS !important Rule

A Guide to Specificity and Maintainable Code

May 11, 2021·

3 min read

Have you ever encountered a situation where you wanted to change the color of a label, but despite your best efforts, the color remained unchanged? You probably discovered that there was another CSS rule overriding your intended style. In this blog post, we will delve into the CSS !important rule, its implications, and how to ensure maintainability and readability in your code.

Imagine this scenario: you have a task at hand—to change the color of a label. Seemingly simple, right? You confidently create a class for the label.

.red-label { color: red; }

Excitedly, you initiate the build, but to your surprise, the label stubbornly remains an ugly shade of green. Perplexed, you start debugging your code and discover another rule buried deep within your codebase.

.container label { color: green !important; }

Ah, the source of the problem is now clear. But how do we fix it?

Solution Attempt: Your instinct tells you to add the !important declaration to your class rule.

.red-label { color: red !important; }

Voila! The label finally assumes the desired color, and you rejoice in your accomplishment. But hold on a moment—things are not as ideal as they seem.

What is the problem and how to fix it?

Let's consider the issue at hand. Overspecifying rules by relying heavily on the !important rule can have detrimental effects on code maintainability and readability. While it may seem like a quick fix, it offers no real benefits in the long run.

To comprehend the problem fully, we need to grasp the concept of specificity. CSS stands for Cascading Style Sheets, and as the name suggests, styles cascade and override each other based on their specificity. When multiple rules with the same specificity are applied to an element, the one declared further down in the source code takes precedence.

How to calculate specificity

To calculate specificity, you need to consider the following factors:

  1. Count the number of ID attributes in the selector

  2. Count the number of other attributes and pseudo-classes in the selector

  3. Count the number of element names in the selector

The !important value appended to a CSS property grants it the highest specificity, overriding even inline styles defined within the markup. The only way an !important value can be overridden is by another !important rule declared later in the CSS, as the hierarchy of rules determines which property should be applied to a given element.

Rather than relying on excessive use of the !important rule, it is advisable to employ naming methodologies like BEM (Block Element Modifier) or other similar approaches. These methodologies promote a clear CSS hierarchy and help establish a structured and maintainable codebase.

In conclusion, understanding the CSS !important rule and specificity is crucial for maintaining a robust and readable codebase. While the !important rule can be a powerful tool in certain scenarios, overusing it can lead to difficulties in maintaining and comprehending your stylesheets. By following best practices, such as employing naming methodologies and considering the CSS hierarchy, you can create maintainable code that avoids the pitfalls of overspecificity.

Thank you for reading!