<style>

/*Any screen above of 1000px*/
@media only screen and (min-width: 1000px) {
  *
  {
    background-color: blue !important;
  }
}

/*Any screen bellow of 1000px*/
@media only screen and (max-width: 1000px) {
  *
  {
    background-color: red !important;
  }
}

</style>