微信小程序中背景图片如何占满整个屏幕，拉伸

Question

Answer 1

.backg{
position:fixed;
top:0;
left:0;
width:100%;
height:100%;
background:url('https://dfsn.china-tengyun.com/group1/M00/01/60/cH5Z71tsCSyAbaJdAACoXp7ghWs919.jpg') no-repeat #000;
background-size:cover;
z-index:-1;
}