@-webkit-keyframes scroll {
  0% {
    transform: translateX(0);
  }
  100% {
    transform: translateX(calc(-250px * 15));
  }
}

@keyframes scroll {
  0% {
    transform: translateX(0);
  }
  100% {
    transform: translateX(calc(-250px * 15));
  }
}
.fenster {
  background: white;
 
  height: 100px;
  margin: auto;
  overflow: hidden;
  position: relative;
  width: 100%;
}
.fenster::before, .fenster::after {
  background: linear-gradient(to right, white 0%, rgba(255, 255, 255, 0) 100%);
  content: "";
  height: 100px;
  position: absolute;
  width: 100%;
  z-index: 2;
}
.fenster::after {
  right: 0;
  top: 0;
  transform: rotateZ(180deg);
}
.fenster::before {
  left: 0;
  top: 0;
}
.fenster .fly-track {
  -webkit-animation: scroll 20s linear infinite;
          animation: scroll 50s linear infinite;
  display: flex;
  width: calc(250px * 5);
}
.fenster .fly {
  height: 100px;
  width: 100%;
}