html中背景图不随着鼠标的转动改变大小

直接在页面中设置body的属性就好了，此为备忘录

body {
background:url("Img/allbac.jpg") ;
background-position: center 0;
background-repeat: no-repeat;
background-attachment:fixed;
background-size: cover;
-webkit-background-size: cover;/* 兼容Webkit内核浏览器如Chrome和Safari */
-o-background-size: cover;/* 兼容Opera */
}