css 图片等宽等高
html
<div class="autoimg">
<img src="xxx.jpg" />
</div>
css
.autoimg {
position: relative;
width: 100%;
height: 0;
padding-bottom: 100%;
overflow: hidden;
}
.autoimg img {
position:absolute;
top: 0;
left: 0;
width: 100%;
}