css - 多线链接动画：在之前

:root {
--00a3a3: #00a3a3;
}

a {
position: relative;
text-decoration: none; /* For Example */
background-image: linear-gradient(#00a3a3, #00a3a3);
background-position: 50% 100%;
background-repeat: no-repeat;
background-size: 0% 2px;
transition: background-size .3s;
}

a:hover {
background-size: 100% 2px;
}

<a href="#">test</a>
<br>
<br>
<a href="#">test
<br>
test2
</a>

:root {
  --00a3a3: #00a3a3;
}

a {
  position: relative;
  text-decoration: none;
  /* For Example */
}

a:before,
a:after {
  content: "";
  position: absolute;
  width: 100%;
  height: 2px;
  left: 0;
  background-color: var(--00a3a3);
  visibility: hidden;
  -webkit-transform: scaleX(0);
  transform: scaleX(0);
  -webkit-transition: all 0.3s ease-in-out 0s;
  transition: all 0.3s ease-in-out 0s;
}

a:before {
  bottom: 0;
}

a:after {
  bottom: 1em;
}

a:hover:before,
a:hover:after {
  visibility: visible;
  -webkit-transform: scaleX(1);
  transform: scaleX(1);
}

<a href="#">test</a>
<br>
<br>
<a href="#">test
<br>
test2
</a>