12

1212

HTML

<h3>背景图自适应后</h3>
<div class="bg" style="width:300px; height:300px"></div>
<hr />
<h3>图片原始大小</h3>
<p><img src="https://timgsa.baidu.com/timg?image&quality=80&size=b9999_10000&sec=1535629608404&di=35c6258989ae1df8e10b23a90fdd95d2&imgtype=0&src=http%3A%2F%2Fpic11.nipic.com%2F20101210%2F6157687_095335160000_2.jpg" /></p>

CSS

.bg{
background:url(https://timgsa.baidu.com/timg?image&quality=80&size=b9999_10000&sec=1535629608404&di=35c6258989ae1df8e10b23a90fdd95d2&imgtype=0&src=http%3A%2F%2Fpic11.nipic.com%2F20101210%2F6157687_095335160000_2.jpg);
filter:"progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod='scale')";
-moz-background-size:100% 100%;
    background-size:100% 100%;
}