问使用CSS3动画和Sass @for循环触发列表

EN

<ul>
  <li><a href="#About">About</a></li>
  <li><a href="#Contact">Contact</a></li>
  <li><a href="Labs">Labs</a></li>
</ul>

html {
  font-size: 62.5%;
   box-zising: border-box;
}

*,
*:before,
*:after {
  box-zising: inherit;
}

html, body {
  width: 100vw;
  height: 100vh;
  background: black;
  font-size: 1rem;
}


ul {
  position: fixed;
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  border: 1px solid white;
  width: 100vw;
  height: 100vh;
}

li {
  list-style: none;
  border: 1px solid white;
  width: 100%;
  text-align: center;
  margin-top: 10px;
  background: red;

  @for $i from 1 through 4 {
    &:nth-of-type(#{$i}) {
      animation: slideTop;
      animation-duration: 1.5s + (40ms * $i);
      animation-iteration-count: 5;
      animation-delay: 2.5s + (40ms * $i);
    }
  }

  a {
    display: block;
    padding: 50px;
    color: white;
    font-size: 24px;
    text-decoration: none;
    letter-spacing: 0.1em;
  }
}


@keyframes slideTop {
  0% {
    opacity: 0;
    transform: scaleY(0);
  }
  100% {
    opacity: 1;
    transform: scaleY(50px);
  }
}