需要保持高宽比的图，可以用 padding-top 实现

<template>
  <div class="border m-4 img-container">
    <img src="/logo.png" alt="" />
  </div>
</template>

<style lang="less">
  .img-container {
    position: relative;
    padding-top: 100% * (250/750);
    height: 0;
    overflow: hidden;
    img {
      width: 100%;
      height: auto;
      position: absolute;
      left: 0;
      top: 0;
    }
  }
</style>

.img-container {
  position: relative;
  // 实现宽高比为 100:750 的图片区域
  padding-top: 100% * (250/750);
  height: 0;
  overflow: hidden;
  img {
    width: 100%;
    height: auto;
    position: absolute;
    left: 0;
    top: 0;
  }
}