less.js/test/less/mixins.less

.mixin { border: 1px solid black; }
.mixout { border-color: orange; }
.borders { border-style: dashed; }

#namespace {
  .borders {
    border-style: dotted;
  }
  .biohazard {
    content: "death";
    .man {
      color: transparent;
    }
  }
}
#theme {
  > .mixin {
    background-color: grey;
  }
}
#container {
  color: black;
  .mixin;
  .mixout;
  #theme > .mixin;
}

#header {
  .milk {
    color: white;
    .mixin;
    #theme > .mixin;
  }
  #cookie {
    .chips {
      #namespace .borders;
      .calories {
        #container;
      }
    }
    .borders;
  }
}
.secure-zone { #namespace .biohazard .man; }
.direct {
  #namespace > .borders;
}