html - 背景响应和覆盖

Question

为什么当我缩小窗口时，第二个 div 响应(背景调整大小为真)，第二个没有？

.imga {
  height: 450px;
  background-image: url(https://img15.hostingpics.net/pics/5638130f9bd1dbafdaabbd88d207439290c1dd206e3d68f201696a5e15b2185756a209.png);
  background-size: cover;
}

.imgb {
  height: 450px;
  background-image: url(https://mdn.mozillademos.org/files/8971/firefox_logo.pn);
  background-size: cover;
}

<div class="imga">

</div>

<div class="imgb">

</div>

谢谢你:)

Answer 1

因为background-size 封面:

Scales the image as large as possible without stretching the image. If the proportions of the image differ from the element, it is cropped either vertically or horizontally so that no empty space remains.

总结:如果它更小，请加宽。如果它更大，请将其切掉。