What is css cascading

css cascading refers to how the browser decides which rule will be applied to the element when multiple CSS rules are applied to the same element at the same time in an HTML document, and how to handle conflicts between rules. The CSS cascading mechanism works based on a series of rules and priorities that determine which styles will be applied to elements and which style will take precedence when multiple styles conflict. The order of rules is browser default style, external style sheet, internal style sheet, and inline style.

The operating system for this tutorial: Windows 10 system, DELL G3 computer.

CSS cascading is one of the very important concepts in front-end development. It refers to how the browser decides which rule will be applied to the element in an HTML document when multiple CSS rules are applied to the same element at the same time, and how to handle conflicts between rules.

The CSS cascading mechanism works based on a series of rules and priorities. These rules and priorities determine which styles will be applied to elements, and which style will take precedence when multiple styles conflict. Below we will introduce the rules and priorities of CSS cascading in detail.

First of all, CSS cascading rules are processed in a specific order. The order is:

1. Browser default styles: The browser will define some default styles for each HTML element. These styles are usually defined by browser manufacturers to ensure that the page can display normally without CSS styles.

2. External style sheet: External style sheet is a method that defines CSS styles in a separate file and then references them in the HTML document. When a browser parses an HTML document, it first loads the external style sheet and applies the styles from it.

3. Internal style sheet: Internal style sheet is a method of defining CSS styles in the `

4. Inline styles: Inline styles are a method of applying CSS styles directly to HTML elements. It is implemented by defining the style in the element's `style` attribute. Inline styles have the highest priority because they are applied directly to the element.

When multiple style rules are applied to the same element, the CSS cascading mechanism will determine which style will be applied based on the following priority rules:

1. Importance: By using `! The important` keyword can mark a style rule as important. Important style rules will override other non-important rules.

2. Priority: Each style rule has a priority, which is determined by the specificity and source of the selector. Specificity is a value used to measure the priority of a selector, which is composed of the number of elements, classes, IDs, and pseudo-classes in the selector. Source refers to the location where the style rule is defined, such as external style sheets, internal style sheets, and inline styles.

3. Order: If two style rules have the same priority and specificity, which style will be applied is determined based on their order in the style sheet. Style rules defined later will override rules defined earlier.

To sum up, the CSS cascading mechanism determines which style will be applied to elements through a series of rules and priorities. Understanding these rules and priorities is crucial for front-end developers because they help us better control and manage the styling of web pages.

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