Flex layout belongs to bootstrap; flex refers to elastic layout. Bootstrap can control the layout of the page through the flex class. Use ".d-flex" and ".d-inline-flex" to enable the flex layout style , whether you can use flex elastic layout is also the biggest difference between bootstrap3 and bootstrap4.
The operating environment of this tutorial: Windows 10 system, bootstrap version 5, DELL G3 computer
flex belongs to bootstrap
Bootstrap4 controls the layout of the page through the flex class
The biggest difference between Bootstrap 3 and Bootstrap 4 is that Bootstrap 4 uses flexible boxes for layout instead of floats.
Use .d-flex and .d-inline-flex to enable flex layout style;
.flex-row can render child elements The position in the horizontal direction, the default is left and displayed from left to right (1,2,3);
.flex-row-reverse sub-element is positioned horizontally on the right and displayed from left to right (3, 2, 1);
.flex-column realizes the vertical effect of child elements and displays (1, 2, 3) from top to bottom;
.flex-column-reverse realizes the vertical effect of child elements and displays (3, 2, 1) from top to bottom;
.justify-content-start (end, center, between, around) realizes content alignment;
.align-items-start (end, center, baseline, stretch) realizes item alignment;
.align-self-start(end, center, baseline, stretch) achieves single-item alignment;
The example is as follows:
<div class="d-flex flex-row-reverse border border-dark mt-5 justify-content-center">
<div class="p-2 border border-success">
1 </div>
<div class="p-2 border border-success">
2 </div>
<div class="p-2 border border-success">
3 </div>
</div>
<div class="d-flex flex-column-reverse border border-dark mt-5 justify-content-between" style="height: 200px;">
<div class="p-2 border border-success">
1 </div>
<div class="p-2 border border-success">
2 </div>
<div class="p-2 border border-success">
3 </div>
</div>
<div class="d-flex border border-dark mt-5 align-items-baseline" style="height: 200px;">
<div class="p-2 border border-success align-self-center">
1 </div>
<div class="p-2 border border-success">
2 </div>
<div class="p-2 border border-success">
3 </div>
</div>The example is as follows :
<!DOCTYPE html>
<html>
<head>
<title>Bootstrap 实例</title>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="https://cdn.staticfile.org/twitter-bootstrap/4.3.1/css/bootstrap.min.css">
<script src="https://cdn.staticfile.org/jquery/3.2.1/jquery.min.js"></script>
<script src="https://cdn.staticfile.org/popper.js/1.15.0/umd/popper.min.js"></script>
<script src="https://cdn.staticfile.org/twitter-bootstrap/4.3.1/js/bootstrap.min.js"></script>
</head>
<body>
<div class="container mt-3">
<h2 id="Flex">Flex</h2>
<p>使用 d-flex 类创建一个弹性盒子容器，并设置三个弹性子元素：</p>
<div class="d-flex p-3 bg-secondary text-white">
<div class="p-2 bg-info">Flex item 1</div>
<div class="p-2 bg-warning">Flex item 2</div>
<div class="p-2 bg-primary">Flex item 3</div>
</div>
</div>
</body>
</html>Output result:
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