5-6 @warn

@mixin adjust-location($x, $y) { @if unitless($x) {//unitless是内置函数，判断数值是否有“单位” @warn "Assuming #{$x} to be in pixels"; $x: 1px * $x; } @if unitless($y) { @warn "Assuming #{$y} to be in pixels"; $y: 1px * $y; } position: relative; left: $x; top: $y; } .botton{ @include adjust-location(20px, 30); }