*, *::before, *::after {
	box-sizing: border-box;
}
.bird {
	background-image: url(https://i.imgur.com/WOuT4Z0.png);
	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-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 {
	animation-duration: 14.6s;
	animation-delay: 9.5s;
}
.bird-container--four {
	animation-duration: 16s;
	animation-delay: 10.25s;
}
@keyframes fly-cycle {
	100% {
		background-position: -900px 0;
   }
}
@keyframes fly-right-one {
	0% {
		transform: scale(0.3) translateX(-10vw);
   }
	10% {
		transform: translateY(0vh) translateX(10vw) scale(0.4);
   }
	20% {
		transform: translateY(2vh) translateX(30vw) scale(0.5);
   }
	30% {
		transform: translateY(10vh) translateX(50vw) scale(0.6);
   }
	40% {
		transform: translateY(2vh) translateX(70vw) scale(0.6);
   }
	50% {
		transform: translateY(0vh) translateX(90vw) scale(0.4);
   }
	60% {
		transform: translateY(0vh) translateX(100vw) scale(0);
   }
	100% {
		transform: translateY(0vh) translateX(100vw) scale(0);
   }
}
@keyframes fly-right-two {
	0% {
		transform: translateY(-2vh) translateX(-10vw) scale(0.5);
   }
	10% {
		transform: translateY(0vh) translateX(10vw) scale(0.4);
   }
	20% {
		transform: translateY(-4vh) translateX(30vw) scale(0.6);
   }
	30% {
		transform: translateY(1vh) translateX(50vw) scale(0.45);
   }
	40% {
		transform: translateY(-2.5vh) translateX(70vw) scale(0.5);
   }
	50% {
		transform: translateY(0vh) translateX(90vw) scale(0.45);
   }
	51% {
		transform: translateY(0vh) translateX(110vw) scale(0.45);
   }
	100% {
		transform: translateY(0vh) translateX(110vw) scale(0.45);
   }
}