You can use LESS's nested syntax in order to generate prefixed CSS classes instead of nested CSS selectors, if you prefer them. That gives you the advantage of prefixed CSS classes, but you don't have to repeat the prefix and you have all classes with the same prefix grouped together, which IMHO makes large projects easier to maintain.

  .textfield {
    &-label {
      ...
    }
    &-input {
      ...
    }
  }