Why do pseudo-elements fail?

Reasons why pseudo elements are invalid: 1. Selector issues; 2. Style conflicts; 3. Inheritance issues; 4. Syntax errors; 5. Browser compatibility issues, etc. Detailed introduction: 1. Selector problem, the selector of the pseudo element may be incorrect, resulting in the target element not being selected; 2. Style conflict, if there is a style conflict in CSS, the pseudo element may become invalid; 3. Inheritance problem, Pseudo elements may not inherit certain style attributes; 4. Syntax errors. If there are syntax errors in CSS, the pseudo elements may fail; 5. Browser compatibility issues, etc.

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

Pseudo-elements are a technique used in CSS to select and manipulate parts of specific elements. They are often used to add some extra style or effect, such as underlining a link or adding some decorative elements. However, sometimes we find that pseudo-elements fail, i.e. they fail to apply the expected style or effect. The following are several reasons that may cause pseudo elements to fail:

1. Selector problem: The selector of the pseudo element may be incorrect, resulting in the inability to select the target element. For example, when using the ::before or ::after pseudo-element, you need to specify which element is selected before or after. If the selector is incorrect, the pseudo-element will not take effect.

2. Style conflict: If there is a style conflict in CSS, it may cause the pseudo element to fail. For example, if an element's style is overridden by another style, that element's pseudo-elements will also be overridden.

3. Inheritance problem: Pseudo elements may not inherit certain style attributes. For example, if the color attribute of the parent element is set to inherit, but the color attribute of the child element is not set, the pseudo-element of the child element will not inherit the color attribute value of the parent element.

4. Syntax error: If there is a syntax error in CSS, it may cause the pseudo element to fail. For example, if an invalid selector or attribute name is used, or if the attribute value does not conform to the specification, the entire CSS rule will be ignored.

5. Browser compatibility issues: Different browsers have different levels of support for CSS, and some browsers may not support certain pseudo elements or attributes. If you use pseudo-elements or attributes that are not supported by the target browser, they will not take effect.

In order to solve the problem of pseudo-element failure, you can take the following measures:

1. Check whether the selector and style are correct: Confirm whether the selector and style of the pseudo-element are correct, and ensure that they comply with expected.

2. Resolve style conflicts: If there is a style conflict, you can resolve the conflict by adjusting the priority of CSS rules or using different selectors.

3. Check the inheritance relationship: If the pseudo element cannot inherit certain style attributes, you can manually set the required attribute values.

4. Check for grammatical errors: Check the CSS code carefully to ensure that there are no grammatical errors that cause the rules to be invalid.

5. Test browser compatibility: Test the page in different browsers to ensure that the pseudo elements and attributes used can work properly in the target browser.

6. Use developer tools: Use the browser's developer tools to easily check and debug CSS code to help find the problem.

7. Check the documents and information: Check the relevant CSS documents and information to understand the usage and limitations of pseudo elements in order to better solve the problem.

In short, to solve the problem of pseudo-element failure, you need to carefully check the code and analyze the cause of the problem, and then take appropriate measures to repair and optimize.

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