@import url("https://fonts.googleapis.com/css?family=Arima+Madurai:300");

.animated-birds {
  position: fixed;
  inset: 0;
  overflow: hidden;
  pointer-events: none;
  z-index: 1;
}

.bird {
  background-image: url("https://s3-us-west-2.amazonaws.com/s.cdpn.io/174479/bird-cells-new.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;
  filter: drop-shadow(0 0 6px rgba(0, 0, 0, 0.4));
  opacity: 0.85;
}

.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.reverse {
  left: auto;
  right: -10%;
  transform: scale(0) translateX(120vw);
  animation-name: fly-left-one;
}
.bird-container.reverse .bird {
  transform: scaleX(-1);
}
.bird-container--one {
  animation-duration: 15s;
  animation-delay: 0s;
}
.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(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%,
  100% {
    transform: translateY(0vh) translateX(110vw) scale(0.6);
  }
}

@keyframes fly-left-one {
  0% {
    transform: scale(0.3) translateX(120vw);
  }
  10% {
    transform: translateY(2vh) translateX(90vw) scale(0.4);
  }
  20% {
    transform: translateY(0vh) translateX(60vw) scale(0.5);
  }
  30% {
    transform: translateY(4vh) translateX(30vw) scale(0.55);
  }
  40% {
    transform: translateY(2vh) translateX(0vw) scale(0.6);
  }
  50% {
    transform: translateY(0vh) translateX(-30vw) scale(0.6);
  }
  60% {
    transform: translateY(2vh) translateX(-60vw) scale(0.6);
  }
  80% {
    transform: translateY(0vh) translateX(-90vw) scale(0.6);
  }
  100% {
    transform: translateY(0vh) translateX(-120vw) scale(0.6);
  }
}

@media (max-width: 768px) {
  .bird-container {
    animation-duration: 18s;
  }
  .bird {
    width: 60px;
    height: 85px;
  }
}

.animated-birds--light .bird {
  filter: brightness(0) invert(1) drop-shadow(0 0 8px rgba(255, 255, 255, 0.35));
  opacity: 0.9;
}