Css3 Animation 动画原则八

<h1>Principle 8: Secondary Action</h1>
<h2><a href="https://cssanimation.rocks/principles/" target="_parent">Animation Principles for the Web</h2>
<article class="principle eight">
    <div class="shape a"></div>
    <div class="shape b"></div>
    <div class="shape c"></div>
</article>

.eight .shape.a {
  transform: translateX(-6em);
  animation: eight-shape-a 4s cubic-bezier(.57,-0.5,.43,1.53) infinite;
}
.eight .shape.b {
  top: calc(50% + 6em);
  opacity: 0;
  animation: eight-shape-b 4s linear infinite;
}
.eight .shape.c {
  transform: translateX(6em);
  animation: eight-shape-c 4s cubic-bezier(.57,-0.5,.43,1.53) infinite;
}

@keyframes eight-shape-a {
  0%, 50% {
    transform: translateX(-5.5em);
  }
  70%, 100% {
    transform: translateX(-10em);
  }
}

@keyframes eight-shape-b {
  0% {
    transform: none;
  }
  20%, 30% {
    transform: translateY(-1.5em);
    opacity: 1;
    animation-timing-function: cubic-bezier(.57,-0.5,.43,1.53);
  }
  32% {
    transform: translateY(-1.25em);
    opacity: 1;
  }
  34% {
    transform: translateY(-1.75em);
    opacity: 1;
  }
  36%, 38% {
    transform: translateY(-1.25em);
    opacity: 1;
  }
  42%, 60% {
    transform: translateY(-1.5em);
    opacity: 1;
  }
  75%, 100% {
    transform: translateY(-8em);
    opacity: 1;
  }
}

@keyframes eight-shape-c {
  0%, 50% {
    transform: translateX(5.5em);
  }
  70%, 100% {
    transform: translateX(10em);
  }
}

/* General styling */
body {
  margin: 0;
  background: #e9b59f;
  font-family: HelveticaNeue, Arial, Sans-serif;
  color: #fff;
}

h1 {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  text-align: center;
  font-weight: 300;
}

h2 {
  font-size: 0.75em;
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  text-align: center;
}

a {
  text-decoration: none;
  color: #333;
}

.principle {
  width: 100%;
  height: 100vh;
  position: relative;
}

.shape {
  background: #2d97db;
  border: 1em solid #fff;
  width: 4em;
  height: 4em;
  position: absolute;
  top: calc(50% - 2em);
  left: calc(50% - 2em);
}