如何访问嵌套的css类

<div class="container">
  <div class="header">
    <h1>Title</h1>
  </div>
  <div class="content">
    <p>Some text here.</p>
  </div>
</div>

.container {
  background-color: #f0f0f0;
  padding: 20px;

  .header {
    background-color: #333;
    color: white;
    padding: 10px;

    h1 {
      margin: 0;
    }
  }

  .content {
    margin-top: 20px;

    p {
      font-size: 16px;
    }
  }
}

.container {
  background-color: #f0f0f0;
  padding: 20px;
}
.container .header {
  background-color: #333;
  color: white;
  padding: 10px;
}
.container .header h1 {
  margin: 0;
}
.container .content {
  margin-top: 20px;
}
.container .content p {
  font-size: 16px;
}