How to Override Website CSS Styles with Custom CSS Using Specificity?

Overriding Website CSS Styles with Custom CSS

Your website consists of three automatically included CSS files, and you lack access to the index.html file. However, you have control over the website's CSS files and intend to create a new CSS file to override the existing ones.

While using @import url(css4.css) may have been your first attempt, it failed to override the last CSS file's styling. This issue stems from the concept of "CSS specificity."

CSS Specificity

CSS specificity determines the precedence of style declarations on an element. It consists of four components:

• Inline: Styles applied directly to an element
• Id: Styles applied to an element with an ID
• Class: Styles applied to an element with a class
• Element: Styles applied to any instance of a particular element type

The weight of each component is represented in the following format: inline | id | class | element. The higher the weight in any column, the higher the specificity.

Resolving Specificity Conflicts

To override existing CSS styles, you must ensure that your new CSS has a higher specificity than the conflicting styles. For instance, if the existing CSS uses a class selector, you must use an ID or inline selector in your custom CSS.

Breaking Down the Specificity Example

The provided code illustrates CSS specificity in action:

<code class="css">body {margin: 0;padding: 0}
div,article {min-height: 200px;height: 100%;width: 100%}
#id {background-color: green}
.class {background-color: yellow }
section {background-color: blue }
.inline {background-color: purple !IMPORTANT }</code>

The <div> with the inline style of background-color: red will appear purple despite the inline style having a higher specificity (1|0|0|0). This is because the custom CSS sets !important on the .inline class, indicating that its style should override all others.

Conclusion

Understanding CSS specificity allows you to precisely control the presentation of your website's elements. By deliberately using higher specificity values, you can easily override existing CSS styles and create custom designs without having to edit the original index.html file.

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