<style>
.videowrapper {
position: relative;
padding-bottom: 56.25%; /* 16:9 비율인 경우 */
/* padding-bottom값은 4:3 비율인 경우 75%로 설정합니다 */
padding-top: 25px;
height: 0;
}
.videowrapper iframe {
position: absolute;
top: 0;
left: 0;
width: 100%;
height: 100%;
}
</style>
<div class="videowrapper">
<iframe width="560" height="315" src="https://player.vimeo.com/video/코드?autoplay=1&loop=1&title=0&background=1" allow="autoplay; fullscreen; picture-in-picture" frameborder="0" allowfullscreen></iframe>
</div>