Sample of nested LESS extend use

extend-sample.less

// Here is what I have in the LESS
.furniture-details {
	text-align: justify;
	*, *:before, *:after {
	  -moz-box-sizing: border-box; -webkit-box-sizing: border-box; box-sizing: border-box;
	}
	.detail-column {
		display: inline-block;
		vertical-align: top;
		text-align: left;
	}
	.visuals {
		&:extend( .furniture-details .detail-column );
		width: 42%;
	}
	.specs {
		&:extend( .furniture-details .detail-column );
		width: 52%;
	}
	&:after{
	  content: '';
	  display: inline-block;
	  width: 100%;
	}
}

// This is what is returned after processing
.furniture-details {
  text-align: justify;
}
.furniture-details *,
.furniture-details *:before,
.furniture-details *:after {
  -moz-box-sizing: border-box;
  -webkit-box-sizing: border-box;
  box-sizing: border-box;
}
.furniture-details .detail-column,
.furniture-details .visuals,
.furniture-details .specs {
  display: inline-block;
  vertical-align: top;
  text-align: left;
}
.furniture-details .visuals {
  width: 42%;
}
.furniture-details .specs {
  width: 52%;
}
.furniture-details:after {
  content: '';
  display: inline-block;
  width: 100%;
}