body {
  background:palevioletred;
}

div {
  width: 100%;
  height: 200px;
  background:#fff;
  margin:0 auto;
}

@media screen and (max-width:1000px) {
  body {
    background:red;
  }
  div {
    width:70%;
  }
}
@media screen and (max-width:600px) {
  body {
    background:yellowgreen;
  }
  div {
    display: none;
  }
}