同一個欄可以有多個斷點樣式，讓網頁在不同螢幕尺寸呈現不同佈局
ex：當瀏覽器超過992px會採用 .col-lg-4樣式，當瀏覽器小於576px會採用 .col-sm-8樣式
multi_breakpoint.htm
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>col-{breakpoint}-auto</title>
<!-- Bootstrap CSS -->
<link href="https://cdn.jsdelivr.net/npm/bootstrap@5.2.0-beta1/dist/css/bootstrap.min.css" rel="stylesheet" integrity="sha384-0evHe/X+R7YkIZDRvuzKMRqM+OrBnVFBL6DOitfPri4tjfHxaWutUpFmBp4vmVor" crossorigin="anonymous">
</head>
<Style>
html, body {height: 100%;}
.container{border:0px solid;background-color:#e5e5e5;}
.col{background-color:#ff0000;height:50px;margin-top:10px}
.col-lg-4{background-color:#ff9900;height:50px;margin-top:10px}
.col-lg-8{background-color:#ffffcc;height:50px;margin-top:10px}
.col-sm-8{background-color:#ff9900;height:50px;margin-top:10px}
.col-sm-4{background-color:#ffcc00;height:50px;margin-top:10px}
</style>
<body>
<div class="container">
<div class="row">
<div class="col-lg-4 col-sm-8">.col-lg-4 .col-sm-8</div>
<div class="col-lg-8 col-sm-4">.col-lg-8 .col-sm-4</div>
</div>
</div>
<!-- Bootstrap JS -->
<script src="https://cdn.jsdelivr.net/npm/bootstrap@5.2.0-beta1/dist/js/bootstrap.bundle.min.js" integrity="sha384-pprn3073KE6tl6bjs2QrFaJGz5/SUsLqktiwsUTF55Jfv3qYSDhgCecCxMW52nD2" crossorigin="anonymous"></script>
<script>
let box = document.querySelector('.container');
box.insertAdjacentHTML("afterend", "<div style='text-align:center'>container寬度："+box.clientWidth+"px</div>");
</script>
</body>
</html>