#fader {
        position: fixed;
        top: 0;
        left: 0;
        width: 100%;
        height: 100%;
        z-index: 999999;
        pointer-events: none;
        background: #a9a9a9;
        animation-duration: 400ms;
        animation-timing-function: ease-in-out;
      }

      #fader:before {
        content: '';

      }

      @keyframes fade-out {
        from { opacity: 1 }
        to { opacity: 0 }
      }

      @keyframes fade-in {
        from { opacity: 0 }
        to { opacity: 1 }
      }

      #fader.fade-out {
        opacity: 0;
        animation-name: fade-out;
      }

      #fader.fade-in {
        opacity: 1;
        animation-name: fade-in;
      }