css 保持元素宽高比布局

<div class="container">
    <div class="item">
        <div class="content">

        </div>
    </div>
</div>

.container{
  width: 50%;
  position: relative;
  .item{
    padding-top:75%;
    background-color: #000;
    .content{
      position: absolute;
      inset: 0;
      background-color: red;
    }
  }
}