Button-hover 02

HTML

<div class="container">
  <a href="#">
    <span></span>
    <span></span>
    <span></span>
    <span></span>
    Button
  </a>
</div>  

CSS

body {
  margin: 0;
  padding: 0;
  background: #34495e;
  font-family: sans-serif;
}
.container {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
}
a {
  position: absolute;
  transform: translate(-50%, -50%);
  padding: 20px 40px;
  color: #3498db;
  text-transform: uppercase;
  letter-spacing: 2px;
  font-size: 26px;
  text-decoration: none;
  box-shadow: 0 0 40px rgba(0, 0, 0, .5);
  /* overflow: hidden; */
}
a::before {
  content: '';
  position: absolute;
  top: 2px;
  left: 2px;
  bottom: 2px;
  width: 50%;
  background: rgba(255, 255, 255, .2);
}
a:hover span:nth-child(1) {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 2px;
  background: linear-gradient(to right, #34495e,#3498db);
  animation: span1 2s linear infinite;
}
@keyframes span1 {
  0% {
    transform: translateX(-100%);
  }
  100% {
    transform: translateX(100%);
  }
}
a:hover span:nth-child(2) {
  position: absolute;
  top: 0;
  right: 0;
  width: 2px;
  height: 100%;
  background: linear-gradient(to bottom, #34495e,#3498db);
  animation: span2 2s linear infinite;
}
@keyframes span2 {
  0% {
    transform: translateY(-100%);
  }
  100% {
    transform: translateY(100%);
  }
}
a:hover span:nth-child(3) {
  position: absolute;
  bottom: 0;
  right: 0;
  width: 100%;
  height: 2px;
  background: linear-gradient(to left, #34495e,#3498db);
  animation: span3 2s linear infinite;
}
@keyframes span3 {
  0% {
    transform: translate(100%);
  }
  100% {
    transform: translateX(-100%);
  }
}
a:hover span:nth-child(4) {
  position: absolute;
  bottom: 0;
  left: 0;
  width: 2px;
  height: 100%;
  background: linear-gradient(to top, #34495e,#3498db);
  animation: span4 2s linear infinite;
}
@keyframes span4 {
  0% {
    transform: translateY(100%);
  }
  100% {
    transform: translateY(-100%);
  }
}

Demo

Description

nth-child(n): 选择对应的第 n 个元素
background: linear-gradient: 背景色设置渐变色
animation: span1 2s linear infinite;: 设置动画 持续 2s 速度恒定 无限循环

动画效果，从 X 为-100% 位置-> 100%

@keyframes  span1 {
0% {
    transform: translateX(-100%);
    }
100% {
    transform: translateX(100%);
    }
}