HTML Layout Guide: How to Use Pseudo-Elements for Background Decoration

HTML Layout Guide: How to Use Pseudo Elements for Background Decoration

Abstract:
In HTML page design, background decoration is to improve the page beauty and user experience an important part of. This article will introduce how to use pseudo elements in CSS to implement background decoration and provide specific code examples.

Introduction:
With the development of the Internet and people's pursuit of exquisite design, the importance of web design has become more and more prominent. As an important part of page design, background decoration plays a key role in enhancing user experience and improving page aesthetics. In previous versions of HTML and CSS, the implementation of background decoration usually required the use of background images or complex CSS styles. However, using pseudo elements in CSS, we can implement background decoration in a more concise and flexible way without using additional image resources. Next, this article will provide some specific code examples showing how to use pseudo-elements for background decoration.

1. Introduction to pseudo elements

1. ::before and ::after: Pseudo elements are the key to realizing background decoration. In CSS, we can use the ::before and ::after selectors to insert pseudo elements and perform style modifications before and after the specified elements. These two pseudo-elements respectively represent virtual elements inserted before and after the content of the specified element, and can be used to achieve various background decoration effects.

2. Example demonstration
The following are several specific examples of using pseudo elements for background decoration:

1. Rounded corner background box:

   <style>
    .box {
        position: relative;
        width: 200px;
        height: 200px;
        background: #e5e5e5;
        border-radius: 20px;
    }
   
    .box::before {
        content: "";
        position: absolute;
        top: -10px;
        left: -10px;
        right: -10px;
        bottom: -10px;
        background: linear-gradient(45deg, #ff5f6d, #ffc371);
        border-radius: 30px;
        z-index: -1;
    }
   
    .box::after {
        content: "";
        position: absolute;
        top: 10px;
        left: 10px;
        right: 10px;
        bottom: 10px;
        background: #ffffff;
        border-radius: 30px;
        z-index: -1;
    }
   </style>
   
   <div class="box"></div>

   The above code demonstrates a rounded background box. By inserting two pseudo-elements::before and ::after on the specified element, and specifying the background style and position respectively, we can implement a rounded border with inner and outer color gradients.

2. Wavy bottom border:

   <style>
    .box {
        position: relative;
        width: 300px;
        height: 200px;
        background: #ffffff;
        margin-top: 50px;
    }
   
    .box::before,
    .box::after {
        content: "";
        position: absolute;
        bottom: -50px;
        height: 50px;
        width: 100%;
        background: url(wave.png) repeat-x;
    }
   
    .box::before {
        left: -100px;
        background-position: 0 100%;
    }
   
    .box::after {
        right: -100px;
        background-position: 0 0;
    }
   </style>
   
   <div class="box"></div>

   The above code demonstrates a wavy bottom border. By inserting two pseudo-elements::before and ::after on the specified element, and setting their position and background style, we can achieve a bottom border with a wavy shape.

3. Summary
This article introduces how to use pseudo elements in CSS to achieve background decoration, and provides specific code examples. By using pseudo elements, we can implement background decoration in a more concise and flexible way, eliminating the tedious steps of using background images or complex CSS styles. These examples are just the tip of the iceberg. You can use pseudo elements flexibly according to your needs to achieve various background decoration effects and improve the beauty and user experience of the page.

Reference link:

• CSS pseudo-elements: https://developer.mozilla.org/zh-CN/docs/Web/CSS/Pseudo-elements

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