rulesets.less

#first > .one {
  > #second .two > #deux {
    width: 50%;
    #third {
      &:focus {
        color: black;
        #fifth {
          > #sixth {
            .seventh #eighth {
              + #ninth {
                color: purple;
              }
            }
          }
        }
      }
      height: 100%;
    }
    #fourth, #five, #six {
      color: #110000;
      .seven, .eight > #nine {
        border: 1px solid black;
      }
      #ten {
        color: red;
      }
    }
  }
  font-size: 2em;
}