使用background-attachment：fixed固定背景图以及ios系统不兼容网页背景图片固定的解决方案

解决办法：

body{

width: 100%;

background-image:url('url);

background-repeat: no-repeat;

background-position: center;

background-attachment: fixed;

z-index: -1;

}

兼容性：

body:before {

content: ’ ';

position: fixed;

z-index: -1;

top: 0;

right: 0;

bottom: 0;

left: 0;

background: url('url) center 0 no-repeat;

background-size: cover;

}