Question

<header class="bar bar-nav">
  <h1 class='title'>栅格</h1>
</header>
<div class="content">
  <div class="content-padded grid-demo">
    <div class="row">
      <div class="col-50">50%</div>
      <div class="col-50">50%</div>
    </div>
    <div class="row">
      <div class="col-33">33%</div>
      <div class="col-33">33%</div>
      <div class="col-33">33%</div>
    </div>
    <div class="row">
      <div class="col-20">20%</div>
      <div class="col-80">80%</div>
    </div>
    <h2>无间距</h2>
    <div class="row no-gutter">
      <div class="col-20">20%</div>
      <div class="col-80">80%</div>
    </div>
  </div>
</div>