Add these to your CSS stylesheet as necessary.

CSS to be used only on Mobile devices

This CSS will be used when the screen width is less than 576px.

@media screen and (max-width: 576px) {
  .selector {
    property: value;
  }
}

CSS to be used on anything BUT Mobile phones

This CSS will be used when the screen width is greater than 576px.

@media screen and (min-width: 576px) {
  .selector {
    property: value;
  }
}

CSS to be used only on Tablets

This CSS will be used when the screen width is between 576px and 768px.

@media screen and (min-width: 576px) and (max-width: 768px) {
  .selector {
    property: value;
  }
}