What is the box model

The box model is a way of describing the space occupied by HTML elements on a page. The box model treats each HTML element as a rectangular box, which is composed of four main parts: content area, inner edge padding, borders and margins. Detailed introduction: 1. The content area is the part of the HTML element that actually contains content, such as text, images or other nested elements. This is the core of the box model and determines the actual content displayed by the element; 2. The padding is the content area The white space between the element's border and the padding-top property in CSS.

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

"Box Model" (Box Model) is an important concept in CSS, used to describe the way HTML elements occupy space on the page. The box model treats each HTML element as a rectangular box that consists of four main parts: content area, padding, borders, and margins. Understanding the box model is key to front-end development because it determines how page elements are laid out and rendered. In this article, I will explain in detail the various components of the box model and what they do.

Components of the box model:

Content Area:

The content area is the part of the HTML element that actually contains content, such as text , images, or other nested elements. This is the core of the box model and determines the actual content displayed by the element.

Padding:

Padding is the blank area between the content area and the element border. It can be set in CSS using properties such as padding-top, padding-right, padding-bottom and padding-left. Padding controls the distance between an element's internal content and its border.

Border:

A border is a line or border around content and padding. Borders can be set in CSS using properties such as border-width, border-style and border-color. It is used to decorate and separate the content of an element.

Margin:

The margin is the blank area between the element border and surrounding elements. It can be set in CSS using properties such as margin-top, margin-right, margin-bottom and margin-left. Margins are used to control the distance between an element and other elements.

How the box model works:

When the browser renders the page, it determines the total width and height of each HTML element based on the definition of the box model. These dimensions determine the position and layout of elements on the page. Here's how the box model works:

Total Width: The total width of an

element is equal to the width of the content area plus the width of the left and right padding and left and right borders, plus The width of the top left and right margins.

Total width = content width left padding right padding left border width right border width left outer margin right outer margin

Total Height:

The total height of an element is equal to the height of the content area plus the height of the top and bottom padding and top and bottom borders, plus the height of the top and bottom margins.

Total height = content height, top padding, bottom padding, top border height, bottom border height, top margin, bottom margin

Two standards for the box model:

In Web development, there are two main box model standards: W3C standard box model and IE box model.

W3C Standard Box Model:

The W3C Standard Box Model treats the width and height of an element to include only the content area. Padding, borders, and margins do not affect the overall width and height of an element; they are added to the content area.

This is the default behavior of web standards and the box model adopted by most modern browsers.

IE box model:

The IE box model includes the width and height of the element including the content area, padding and borders. Margins do not affect the overall width and height, they are outside the element.

This is the box model adopted by early versions of the Internet Explorer browser, usually simulated by using the CSS property box-sizing: border-box;.

Ways to control the box model:

In CSS, you can use some properties and techniques to control the behavior of the box model:

box- Sizing attribute:

The box-sizing attribute is used to control the behavior of the box model. It can take two values: content-box and border-box.

content-box is the default value, using the W3C standard box model, which specifies that the width and height of the element include the content area, and the padding, borders, and margins will be added outside the content area.

border-box uses the IE box model, which specifies the width and height of the element including the content area, padding and border, and the margins will be added outside the element.

/* 使用box-sizing来指定盒模型的行为 */
.element {
  box-sizing: content-box; /* 默认值，采用W3C标准盒模型 */
}
.element {
  box-sizing: border-box; /* 采用IE盒模型 */
}
padding、border和margin属性：
你可以使用这些属性来控制元素的内边距、边框和外边距的大小。
css
/* 设置内边距 */
.element {
  padding: 10px; /* 上、右、下

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