<div class="post" style="--theme: light;">
  <div class="card">
    <h2>标题</h2>
  </div>
</div>
.post {
  background-color: #efefef;
  padding: 12px;
}

@container style(--theme: light) {
  h2 {
    font-size: 120px;
  }
}

External CSS

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External JavaScript

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