less:避免编译

.box {
  width: ~"calc(300px - 30px)";
}

编译成css

.box {
  width: calc(300px - 30px);
}
 

important提升优先级

.mixin() {
  color: #900;
  background: #F7BE81;
}
h2 {
  .mixin() !important;
}

编译成css

h2 {
  color: #900 !important;
  background: #F7BE81 !important;
}