今天写了个opacity， 竟然less编译不过，上网搜了一个写法

.opacity (@opacity) {    @opacityPercentage: @opacity * 100;    opacity: @opacity;    -ms-filter: ~"progid:DXImageTransform.Microsoft.Alpha(opacity=(@{opacityPercentage}))";     filter: ~"alpha(opacity = (@{opacityPercentage}))";}

in dotless 1.2.3

.opacity (@opacity) {    @opacityPercentage: @opacity * 100;    opacity: @opacity;    -ms-filter: progid:DXImageTransform.Microsoft.Alpha(opacity=(@opacityPercentage));     filter: alpha(opacity = (@opacityPercentage));}