Let's talk about breakpoints and containers in Bootstrap5

This article will take you through the breakpoints and containers in Bootstrap5. I hope it will be helpful to you!

1. Bootstrap5 breakpoints

1.1 Mobile first

Speaking of mobile first, we must first mention responsive design. Responsive interface is to design a page that can adapt to different devices. Responsive design uses media query and other technologies to achieve style adaptation under different devices/windows. It also That is to say, it will display different page layouts to users according to the different devices you use. [Related recommendation: "bootstrap tutorial"]

This is implemented by having a media query technology based on HTML5, which can obtain the screen width, and then use css to use different values ​​under different widths Just css effect.

Mobile first is to first develop an interface suitable for mobile clients, and then adapt the corresponding style according to the situation of the PC. On the contrary, the design idea is to give priority to PC. Which one to choose? The method should be considered based on your habits and which users account for a large proportion. Mobile first is now generally advocated.

1.2 Bootstrap breakpoints

The so-called breakpoint refers to the critical point. This table and its content must be remembered. In addition, especially the class infix, it is often used. This will be demonstrated in detail in the layout of the next section. You only need to read it a few times. It doesn't matter if you can't remember it. You can check it out when the time comes.

##Large (large, wide screen computer) ≥992px##Extra large (extra large, wide screen computer)xlExtra extra large (extra large, high-definition computer or advertising equipment) xxl

As can be seen from the above table, the screen is divided into 6 sizes through 5 breakpoints. Readers only need to understand it first. It will be further introduced in the third section of the grid system.

2. Containers

2.1 Containers are used to hold things

Containers are the most basic layout elements in Bootstrap and are necessary when designing responsive websites using the default grid system. The maximum width of the container can change according to the width of the browser. The use of containers is very simple. Just place the container tag inside the body. Generally speaking, a page only needs one container tag to wrap all other visual content. However, in this demonstration, in order to compare the different The effect of containers, so multiple containers are placed on one page.

2.2 Classification of Bootstrap containers

Bootstrap containers are divided into three types by default:

• . container, the default container, whose width is the maximum width of the previous breakpoint before each response breakpoint.

• .container-fluid, a fluid container that always occupies 100% of the browser width.

• .container-{breakpoint}, breakpoint container. Before reaching the breakpoint, its width always accounts for 100% of the browser width. After reaching the power outage, its width always is the maximum width of the breakpoint. The breakpoint value corresponds to the breakpoint introduced earlier.

The following table shows the container width at different resolutions.

Breakpoint type	Class infix	Resolution
Small, tablet or old laptop)	sm	≥576px
Medium (medium, narrow screen computer)	md	≥768px
	lg
	≥1200px
	≥1400px

#Extra smallSmallMediumLargeX- LargeXX-Large100%540px720px960px1140px 1320px100%540px720px960px1140px1320px100%100%720px960px1140px1320px100%100%100%960px1140px1320px100%100%100%100%1140px1320px100%100%100%100%100%1320px100%100%100%100%100%100%

		≥576px	≥768px	≥992px	≥1200px	≥1400px
.container
.container-sm
.container-md
.container- lg
.container-xl
.container-xxl
.container-fluid

2.3 Container parsing changes with browser width

2.3.1 Simple examples

Some friends may not understand the table in 2.2. I will give you a few examples:

Take container-md as an example. When the screen When the width is less than 768px, the container width accounts for 100% of the screen width. When the screen width is greater than 768px and less than 992px, the container width is always 720px; and when the screen width is greater than 992px and less than 1200px, the container width is always 960px, and so on, the same is true for other breakpoint containers and the default container.

2.3.2 Several characteristics of Bootstrap containers (excluding flow containers)

The width of the container jumps and is not smooth. The width of the interval between each two breakpoints is the same
• The container is borderless before the breakpoint and has margins after the breakpoint. For a 768px screen, the container width is 720px.
• The default container (container) and the small container (container-sm) are currently equivalent, but it is not ruled out that there will be changes in the next step.

2.4 Demo code for container changes with browser width

The following is the demo code under different browser widths, as well as GIF If you don’t understand the rendering, you can download the code and study it yourself. The style part is written by me to set the background color of the container and the interval of each container to facilitate distinction and viewing. It has nothing to do with the container itself.

2.4.1 Demonstration animation

##2.4.2 Demonstration source code

<!doctype html>
<html>
  <head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <meta name="keywords" content="">
    <meta name="description" content="">
    <link href="bootstrap5/bootstrap.min.css" rel="stylesheet">
 
    <title>不同宽度下容器宽度演示</title>
    <style>
      div{background-color: rgba(0, 0, 255, 0.178);padding: 10px;margin: 10px;}
    </style>
  </head>
  <body>
    <div>    默认容器  </div>
    <div>container-sm 100% wide until small breakpoint</div>
    <div>container-md 100% wide until medium breakpoint</div>
    <div>container-lg 100% wide until large breakpoint</div>
    <div>container-xl 100% wide until extra large breakpoint</div>
    <div>container-xxl 100% wide until extra extra large breakpoint</div>
    <div> 流式容器 </div>
 
     <script src="bootstrap5/bootstrap.bundle.min.js" ></script>
  </body>
</html>

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