main{
height: calc(100vh);
background-image: url(../assets/image/background.png) ; //图片导入
background-size: 100% 100%;背景尺寸
width:100vw;
background-clip:content-box; 裁切背景图片 到content (border-box|padding-box|content-box)
}
原文：https://www.cnblogs.com/panjingshuang/p/12713036.html