.bird {
  background-image: url('/img/def/bird.svg');
  background-size: auto 100%;
  width: 88px;
  height: 125px;
  will-change: background-position;
  animation-name: fly-cycle;
  animation-timing-function: steps(10);
  animation-iteration-count: infinite;
}
.bird_one {
  animation-duration: 1s;
  animation-delay: -0.5s;
}
.bird_two {
  animation-duration: 0.9s;
  animation-delay: -0.75s;
}
.bird_three {
  animation-duration: 1.25s;
  animation-delay: -0.25s;
}
.bird_four {
  animation-duration: 1.1s;
  animation-delay: -0.5s;
}
.bird_five {
  animation-duration: 0.9s;
  animation-delay: -0.75s;
}
.bird-container {
  position: absolute;
  top: 20%;
  left: -10%;
  transform: scale(0) translateX(-10vw);
  will-change: transform;
  animation-name: fly-right-one;
  animation-timing-function: linear;
  animation-iteration-count: infinite;
}
.bird-container_one {
  animation-duration: 15s;
  animation-delay: 0;
}
.bird-container_two {
  animation-duration: 16s;
  animation-delay: 1s;
}
.bird-container_three {
  top: 25%;
  animation-duration: 14.6s;
  animation-delay: 9s;
}
.bird-container_four {
  animation-duration: 16s;
  animation-delay: 5s;
}
.bird-container_five {
  top: 30%;
  animation-duration: 16.5s;
  animation-delay: 0.3;
}
@keyframes fly-cycle {
  100% {
    background-position: -900px 0;
  }
}
@keyframes fly-right-one {
  0% {
    transform: scale(0.3) translateX(-10vw);
  }
  8% {
    transform: translateY(2vh) translateX(10vw) scale(0.4);
  }
  20% {
    transform: translateY(0vh) translateX(30vw) scale(0.5);
  }
  30% {
    transform: translateY(4vh) translateX(50vw) scale(0.6);
  }
  40% {
    transform: translateY(2vh) translateX(70vw) scale(0.6);
  }
  50% {
    transform: translateY(0vh) translateX(90vw) scale(0.6);
  }
  60% {
    transform: translateY(0vh) translateX(110vw) scale(0.6);
  }
  100% {
    transform: translateY(0vh) translateX(110vw) scale(0.6);
  }
}