CSS Orientation

This is visible in portrait.
This is visible in landscape.

Code

@media (orientation: landscape) {
  #landscape {
    opacity: 1;
  }
 
  #portrait {
    opacity: 0.1;
  }
}

@media (orientation: portrait) {
  #landscape {
    opacity: 0.1;
  }
   
  #portrait {
    opacity: 1;
  }
}