@media (max-width: 600px) {
  div.media-class {
    color: black;
  }

  .alone, .unused-class {
    color: black;
  }

  #id-in-media {
    color: black;
  }

  body {
    color: black;
  }
}

@media (max-width: 960px){
  .alone, .unused-class {
    color: black;
  }
  *,
  :before,
  :after {
    background: black;
  }
}

@media (max-width: 66666px){
  .unused-class, .unused-class2 {
    color: black;
  }
}