how to set devicePixelRatio in css code example

Example 1: device-pixel-ratio css

/* Exact resolution */
@media (-webkit-device-pixel-ratio: 1) {
  p {
    color: red;
  }
}

/* Minimum resolution */
@media (-webkit-min-device-pixel-ratio: 1.1) {
  p {
    font-size: 1.5em;
  }
}

/* Maximum resolution */
@media (-webkit-max-device-pixel-ratio: 3) {
  p {
    background: yellow;
  }
}

Example 2: @media (min-resolution:1.25dppx),(-webkit-min-device-pixel-ratio:1.25),(min-device-pixel-ratio:1.25){

@media (min-resolution:1.25dppx),(-webkit-min-device-pixel-ratio:1.25),(min-device-pixel-ratio:1.25){