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Detailed explanation of the difference and usage of CSS pseudo-classes and pseudo-elements
Pseudo-classes and pseudo-elements are concepts often used in CSS. They can help us select and style ize specific elements in HTML. Although their names are similar, they have different usage and functions. In this article, we will explain the difference between CSS pseudo-classes and pseudo-elements in detail and give specific code examples.
1. Pseudo-classes
First, let’s explain pseudo-classes. Pseudo-classes are selectors used to select and style specific states or properties in the DOM tree (Document Object Model). Pseudo-classes are usually represented by a colon (:).
For example, when the mouse hovers over a link, we can change the color of the link through the :hover pseudo-class:
a:hover { color: red; }
For example, we can change the background color of the button when the user clicks the button:
button:active { background-color: yellow; }
For example, we can select the even rows in the table and style them:
tr:nth-child(even) { background-color: #f2f2f2; }
2. Pseudo-elements
Next, let’s do Let’s talk about pseudo-elements. Pseudo-elements are used to create and style new elements in the DOM. Pseudo elements are usually represented by double colons (::).
For example, we can add a comment in front of the paragraph:
p::before { content: "注:"; font-weight: bold; }
For example, we can add an arrow icon at the end of the link:
a::after { content: " →"; }
For example, we can set the first letter of the paragraph to uppercase and change its color:
p::first-letter { font-size: 2em; text-transform: uppercase; color: blue; }
Summary:
To summarize, pseudo-classes and pseudo-elements in CSS are very useful tools that help us select and style different states and specific parts of HTML elements. Pseudo-classes are mainly used to select elements in a specific state, while pseudo-elements are mainly used to create and style new elements. Through the flexible use of pseudo-classes and pseudo-elements, we can better control and design our web pages.
I hope this article will help you understand and use CSS pseudo-classes and pseudo-elements!
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