모바일 페이지 유튜브 링크 질문 채택완료

<iframe width="50%" height="210" style="float:left"

<iframe width="50%" height="210" src="https://www.youtube.com/embed/V1s0ZuWVed4" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen style="display:inline-block;"></iframe><iframe width="50%" height="210" src="https://www.youtube.com/embed/1vAdXinH5ck" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen style="display:inline-block;"></iframe>

이런식으로 해도되고. . 
 

<iframe width="50%" height="210" src="https://www.youtube.com/embed/V1s0ZuWVed4" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen style="float:left;"></iframe><iframe width="50%" height="210" src="https://www.youtube.com/embed/1vAdXinH5ck" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen style="float:left;"></iframe>

<style>
.you:after{clear:both;content:"";display:block;  }
.you iframe{float:left; width:50%;  }
</style>

이런식으로 float:left 로 해도 됩니다.