*{
margin:0;
padding:0;
}
body{
background-attachment: fixed;
background-image:url(https://timgsa.baidu.com/timg?image&quality=80&size=b9999_10000&sec=1519992647875&di=d4c8d7f65b34765633ef200cd33f8205&imgtype=0&src=http%3A%2F%2Fh.hiphotos.baidu.com%2Fzhidao%2Fpic%2Fitem%2Fb21c8701a18b87d648680181000828381f30fd02.jpg);
background-size: 100% 100%;
}
.warp{
height:100vh;
background:url(https://timgsa.baidu.com/timg?image&quality=80&size=b9999_10000&sec=1519993395767&di=a5df567339f28ca323d574b3de5a7260&imgtype=0&src=http%3A%2F%2Ffb.topitme.com%2Fb%2F62%2F8c%2F11986802123238c62bo.jpg);
width:100%;

background-size: 100% 100%;
}
background-size:100%;