<div class="container">
  <div class="row">
    <div class="col-sm-3 box">
      <h2>菜單</h2>
    </div>
    <div class="col-sm-9 box1">
      <h2>選單</h2>
    </div>  
  </div>
</div>
<div class="container-fluid mt-5">
  <div class="row">
    <div class="col-sm-3 box">
      <h2>菜單</h2>
    </div>
    <div class="col-sm-9 box1">
      <h2>選單</h2>
    </div>  
  </div>
</div>

<div class="container-fluid mt-5 box2">
  <div class="container">
    <div class="row">
    <div class="col-sm-3 box">
      <h2>菜單</h2>
    </div>
    <div class="col-sm-9 box1">
      <h2>選單</h2>
    </div>  
  </div>
  </div>
</div>
.box{
 background: yellow;
}
.box1{
  background: red;
}
.box2{
  outline: 1px solid black;
}

External CSS

  1. https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/4.5.0/css/bootstrap.min.css

External JavaScript

This Pen doesn't use any external JavaScript resources.