cssbox-sizing的简单介绍

CSS Box Sizing

Introduction:

CSS Box Sizing is a CSS property that allows you to control how the total width and height of an element is calculated. By default, when you set the width and height of an element, it only includes the content area and does not consider the padding, border, and margin. However, with the box-sizing property, you can choose how the total dimensions of an element are calculated, including or excluding the padding and border.

Multiple Levels of Heading:

1. Syntax:

The syntax for the box-sizing property is as follows:

```

box-sizing: content-box | border-box | initial | inherit;

```

- content-box: This is the default value where the width and height of an element only include the content area.

- border-box: The width and height of an element includes the content, padding, and border areas.

- initial: Sets the box sizing property to its default value.

- inherit: Inherits the box sizing property from its parent element.

2. Example:

Consider the following example:

```

.box {

width: 200px;

height: 100px;

padding: 10px;

border: 1px solid black;

box-sizing: border-box;

```

In this example, the box-sizing property is set to border-box, which means the total width and height of the .box element will include the content, padding, and border areas. Therefore, the actual dimensions of the box will be 200px + 2 * 10px (for padding) + 2 * 1px (for border), resulting in a total width of 222px and a total height of 122px.

3. Browser Support:

The box-sizing property is supported by all modern browsers, including Chrome, Firefox, Safari, and Edge. However, it is not supported in Internet Explorer 7 or earlier versions.

Conclusion:

The box-sizing property is a powerful CSS feature that allows you to control how the total dimensions of an element are calculated. By choosing between content-box and border-box, you can easily include or exclude the padding and border areas when setting the width and height of an element. This property is widely supported by modern browsers, making it a valuable tool in web development.