@media screen {
  a {
    color: black;
    height: 8px;
  }
}

a {
  color: red;
  @media screen {
    color: blue;
    height: 10px;
  }
}

a {
  color: beige;
  b {
    color: teal;
    @media screen {
      color: orange;
      c {
        height: 12px;
      }
    }
  }
}