怎么用！在SASS mixin中默认？

I have this SASS mixin:

我有这个SASS mixin:

@mixin micro-clearfix
    &:after,
    &:before
        content: ""
        display: table
    &:after
        clear: both
    * html &
        height: 1% !default
    *+html &
        min-height: 1% !default
@mi