自定义A标签下划线动画效果

效果图演示

Lorem ipsum dolor sit amet ... beatae, quo iure ... consequatur.

HTML代码

<p>Lorem ipsum dolor <a class="fancy-link" href="#">sit amet ... beatae</a>, quo iure ... consequatur.</p>

CSS样式代码

.fancy-link {
   text-decoration: none;
   background-image: linear-gradient(red, red);
   background-repeat: no-repeat;
   background-position: bottom left;
   background-size: 0 3px;
   transition: background-size 500ms ease-in-out;
}
.fancy-link:hover {
   background-size: 100% 3px;
}
a:hover {
   color:red;
}