SOURCE

<!-- Bootstrap CSS  放在head区-->
<link href="https://cdn.jsdelivr.net/npm/bootstrap@5.1.3/dist/css/bootstrap.min.css" 
rel="stylesheet" integrity="sha384-1BmE4kWBq78iYhFldvKuhfTAU6auU8tT94WrHftjDbrCEXSU1oBoqyl2QvZ6jIW3"
 crossorigin="anonymous">

 <div class="container">
  <div class="row">
    <div class="col-sm-8  border border-danger">col-sm-8</div>
    <div class="col-sm-4  border border-success">col-sm-4</div>
  </div>
  <div class="row">
    <div class="col-sm border border-primary">col-sm</div>
    <div class="col-sm border border-danger">col-sm</div>
    <div class="col-sm border border-success">col-sm</div>
  </div>
</div>
<div class="container">
  <!-- Stack the columns on mobile by making one full-width and the other half-width -->
  <div class="row">
    <div class="col-md-8">.col-md-8</div>
    <div class="col-6 col-md-4">.col-6 .col-md-4</div>
  </div>

  <!-- Columns start at 50% wide on mobile and bump up to 33.3% wide on desktop -->
  <div class="row">
    <div class="col-6 col-md-4 bg-light">.col-6 .col-md-4</div>
    <div class="col-6 col-md-4 bg-danger">.col-6 .col-md-4</div>
    <div class="col-6 col-md-4 bg-info">.col-6 .col-md-4</div>
  </div>

  <!-- Columns are always 50% wide, on mobile and desktop -->
  <div class="row">
    <div class="col-6">.col-6</div>
    <div class="col-6">.col-6</div>
  </div>
</div>

<div class="clearfix">
  <img  src="http://www.gysjxjy.com/kejian/gyjj210402/21/courseware/images/000000.jpg" class="col-md-6 float-md-end mb-3 ms-md-3" alt="...">

  <p>
    A paragraph of placeholder text. We're using it here to show the use of the clearfix class. We're adding quite a few meaningless phrases here to demonstrate how the columns interact here with the floated image.
  </p>

  <p>
    As you can see the paragraphs gracefully wrap around the floated image. Now imagine how this would look with some actual content in here, rather than just this boring placeholder text that goes on and on, but actually conveys no tangible information at. It simply takes up space and should not really be read.
  </p>

  <p>
    And yet, here you are, still persevering in reading this placeholder text, hoping for some more insights, or some hidden easter egg of content. A joke, perhaps. Unfortunately, there's none of that here.
  </p>
</div>

<kbd>ALT</kbd>+<kbd>F4</kbd> 关闭窗口
<div  class="invisible">你看不见我</div>
<details>
<summary>概括</summary>
<p>more...</p>
</details>

<!-- Separate Popper and Bootstrap JS 放在body区末尾-->
<script src="https://cdn.jsdelivr.net/npm/@popperjs/core@2.10.2/dist/umd/popper.min.js" 
integrity="sha384-7+zCNj/IqJ95wo16oMtfsKbZ9ccEh31eOz1HGyDuCQ6wgnyJNSYdrPa03rtR1zdB" 
crossorigin="anonymous"></script>
<script src="https://cdn.jsdelivr.net/npm/bootstrap@5.1.3/dist/js/bootstrap.min.js" 
integrity="sha384-QJHtvGhmr9XOIpI6YVutG+2QOK9T+ZnN4kzFN1RtK3zEFEIsxhlmWl5/YESvpZ13" 
crossorigin="anonymous"></script>