<div class="box">
  <span class="title1">title 1</span>
  <span class="title2">title 2</span>
</div>

html{
  font-size: 1vw;
}

.box{
  /*  这个尺寸是根据ue宽600，其中100px对应的rem长度*/
  font-size: 15.625rem;
/*   width: 15.625rem; */
  border: 1px solid;
}

External CSS

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External JavaScript

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