sass中使用at-root 和 @media

SASS代码

header {  position:relative;  display: block;  width: 100%;  height: 100%;  .rule {    width:100%;    text-align: center;    color:#fff;    font-size:14px;    @at-root & {      @media all and (min-height:660px)  {      & {        position:relative;        bottom:0;      }    }    }  }}

编译后

header {  position: relative;  display: block;  width: 100%;  height: 100%;}header .rule {  width: 100%;  text-align: center;  color: #fff;  font-size: 14px;}@media all and (min-height: 660px) {  header .rule {    position: relative;    bottom: 0;  }}