<div class="videoWrapper">
  <!-- Copy & Paste từ YouTube -->
  <iframe width="560" height="315" src="https://www.youtube.com/embed/f3VSBaxcGGg" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>
</div>
.videoWrapper {
  position: relative;
  padding-bottom: 56.25%; /* 16:9 */
  height: 0;
}

.videoWrapper iframe {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
}

External CSS

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External JavaScript

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