官方例子.average(@x, @y) {  @average: ((@x + @y) / 2);}div {  .average(16px, 50px); // "call" the mixin  padding: @average;    // use its "return" value  .average(40px, 50px);  //  這樣就杯具了  margin: @average; // average覆蓋不了}有好的解決方案嗎```` only less