<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width,initial-scale=1,shrink-to-fit-no" />
<link rel="stylesheet" type="text/css" href="css/bootstrap.min.css"/>
<title>demo1</title>
</head>
<body>
<img src="./img/img1.jpg" width="400px" class="border border-success img-thumbnail">
<div class="border border-info m-5" style="width: 100px; height: 100px;">aaaa</div>
<div class="c float-md-start border border-success">left</div>
<div class="c float-md-end border border-success">right</div>
<span class="align-baseline">baseline 基准</span>
<span class="align-text-top">text-top 文本顶部</span>
<span class="align-top">top 顶部</span>
<span class="align-middle">middle 垂直居中</span>
<span class="align-bottom">bottom 底部</span>
<span class="align-text-bottom">text-bottom 文本底部</span>
<table class="table table-bordered" style="height: 200px;">
<tbody>
<tr>
<td class="align-baseline">baseline</td>
<td class="align-top">top</td>
<td class="align-middle">middle</td>
<td class="align-bottom">bottom</td>
<td class="align-text-top">text-top</td>
<td class="align-text-bottom">text-bottom</td>
</tr>
</tbody>
</table>
<style type="text/css">
.c{
width:200px;
height:25px;
}
</style>
<script src="js/bootstrap.bundle.js" type="text/javascript"></script>
</body>
</html>

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width,initial-scale=1,shrink-to-fit-no" />
<link rel="stylesheet" type="text/css" href="css/bootstrap.min.css"/>
<title></title>
</head>
<body>
<div class="d1 bg-warning">
<div class="d2 bg-info m-3">
a
</div>
<span style="font-size: 3em;">d1文字</span>
</div>
<style type="text/css">
html{
}
:root{
font-size: 10px;
}
.d1{
font-size: 10px;
width: 30rem;
}
.d2{
width: 100px;
height: 100px;
font-size: 10px;
}
</style>
<script src="js/bootstrap.bundle.js" type="text/javascript"></script>
</body>
</html>

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width,initial-scale=1,shrink-to-fit-no" />
<link rel="stylesheet" href="./css/bootstrap.min.css">
<title></title>
</head>
<body>
8. 使用.w-*设置元素的长度,包括25%、50%、75%、100%和auto;
<div class="p-3 w-25 bg-info">25%</div>
<div class="p-3 w-50 bg-info">50%</div>
<div class="p-3 w-75 bg-info">75%</div>
<div class="p-3 w-100 bg-info">100%</div>
<div class="p-3 w-auto bg-info">auto</div>
9. 使用.h-*设置元素的高度,包括25%、50%、75%、100%和auto;
<div class="border border-success">
<div class="p-3 h-25 bg-info d-inline-block">25%</div>
<div class="p-3 h-50 bg-info d-inline-block">50%</div>
<div class="p-3 h-75 bg-info d-inline-block">75%</div>
<div class="p-3 h-100 bg-info d-inline-block">100%</div>
<div class="p-3 h-auto bg-info d-inline-block">auto</div>
</div>
10. 使用.mw-*和.mh-*设置max-width 和max-height;
<div class="p-3 mw-100 mh-100 bg-info">max-100%</div>
12. 使用.shadow-*实现元素的阴影效果;
<div class="shadow-none mb-5">Bootstrap4.x</div>
<div class="shadow-sm mb-5">Bootstrap4.x</div>
<div class="shadow mb-5">Bootstrap4.x</div>
<div class="shadow-lg mb-5">Bootstrap4.x</div>
<style type="text/css">
span {
display: inline-block;
}
</style>
<script src="js/bootstrap.bundle.js" type="text/javascript" charset="utf-8"></script>
</body>
</html>
