This is an example of a HTML caption with a link.
最佳解析度1920*1080，文字比例125%，瀏覽器縮放100%
<!-- 16:9 aspect ratio --><div class="embed-responsive embed-responsive-16by9"><iframe height="240" src="https://www.youtube.com/embed/xtvT6ue1_Z0" width="320"></iframe></div>
