Basics
CSS Cascade
The CSS Cascade and Inheritance
CSS cascade governs style application, prioritizing specificity and inheritance.
What is CSS Cascade?
The CSS cascade is a fundamental concept that determines how styles are applied to HTML elements. It resolves conflicts among various CSS rules by considering three main factors: origin, specificity, and inheritance. Understanding these principles helps in creating more predictable and maintainable stylesheets.
Order of Importance in CSS Cascade
The order of importance, also known as the cascade order, is as follows:
- Importance: Styles marked with
!importanthave the highest priority. - Specificity: More specific selectors override less specific ones.
- Source Order: Later styles overwrite earlier ones in the stylesheet.
Understanding Specificity
Specificity is calculated based on the components of a CSS selector:
- Inline styles have the highest specificity.
- ID selectors have higher specificity than class selectors.
- Class selectors have higher specificity than element selectors.
Here is a simple example demonstrating specificity:
In the example above, the text color will be red because the #main .text selector is more specific than the .text class selector or the element selector p.
Role of Inheritance
Inheritance in CSS allows certain properties to be passed from a parent element to its child elements. Not all CSS properties are inherited by default. For example, properties like color and font-family are typically inherited, while properties like margin and border are not.
Here's an illustration of inheritance:
In the above code, the paragraph inside the .parent div inherits the color property, turning the text navy, while the font-size is explicitly set in the p selector.
Conclusion
Understanding the CSS cascade, including specificity and inheritance, is crucial for effective styling. This knowledge helps developers troubleshoot styling issues and write better CSS by predicting how styles will be applied.
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