/* 右の仕様を満たすようにCSSアニメーションを使って実装してみましょう */
* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

ul {
  list-style: none;
}

img {
  vertical-align: bottom;
}

.container {
  padding: 40px 0;
}

.flex {
  display: flex;
  flex-wrap: wrap;
}

.item {
  width: calc(100% / 2);
  text-align: center;
  margin-bottom: 80px;
}

.item-A {
  animation: upDown 4s infinite;
}

@keyframes upDown {
  0% {
    transform: translateY(0);
  }
  25% {
    transform: translateY(-40px);
  }
  100% {
    transform: translateY(0);
  }
}

.item-B {
  animation: sideMove 4s infinite;
}

@keyframes sideMove {
  0% {
    transform: translateX(0);
  }
  25% {
    transform: translateX(40px);
  }
  100% {
    transform: translateX(0);
  }
}

.item-C {
  animation: rotation 3s infinite linear;
}

@keyframes rotation {
  0% {
    transform: rotate(0);
  }
  100% {
    transform: rotate(360deg);
  }
}

.item-D {
  animation: rotation2 3s infinite linear;
}

@keyframes rotation2 {
  0% {
    transform: rotateX(0);
  }
  100% {
    transform: rotateX(360deg);
  }
}

.item-E {
  animation: rotation3 3s infinite linear;
}

@keyframes rotation3 {
  0% {
    transform: rotateY(0);
  }
  100% {
    transform: rotateY(360deg);
  }
}

.item-F {
  animation: rotation4 3s infinite ease-in-out alternate;
}

@keyframes rotation4 {
  0% {
    transform: rotate(0);
  }
  100% {
    transform: rotate(360deg);
  }
}

.item-G {
  animation: swing 2s infinite;
}

@keyframes swing {
  0% {
    transform: rotate(0);
  }
  55% {
    transform: rotate(0deg);
  }
  60% {
    transform: rotate(-10deg);
  }
  65% {
    transform: rotate(8deg);
  }
  70% {
    transform: rotate(-5deg);
  }
  75% {
    transform: rotate(4deg);
  }
  80% {
    transform: rotate(-3deg);
  }
  85% {
    transform: rotate(2deg);
  }
  90% {
    transform: rotate(-1deg);
  }
  95% {
    transform: rotate(1deg);
  }
  100% {
    transfrom: rotate(0);
  }
}

.item-H {
  animation: flash 2s ease-in-out infinite alternate;
}

@keyframes flash {
  0% {
    opacity: 0;
  }
  100% {
    opacity: 1;
  }
}