css3动画边框效果

css3 动画边框效果

HTML 代码：

<section>
  <div >
    <div >
      <div >
        <span></span>
        <span></span>
        <span></span>
        <span></span>
        <div >
          <h2> </h2>
          <p><a>(mybj123.com)是一个前端开发的技术博客，致力于分享学习前端技术的个人心得和技术问题</a></p>
        </div>
        
      </div>
    </div>
  </div>
</section>

CSS 代码：

*{
  margin:0;
  padding:0;
}

.container{
  padding-top: 20px;
  padding-bottom: 20px;
}

body{
  background-color: #111845;
}

.background-img{
  height: 400px;
  width: 800px;
  background-repeat: no-repeat;
  background-size: cover;
  margin: 5% auto;
  padding:20px;
  border: 1px solid #2a3cad;
  border-radius: 4px;
  box-shadow: 0px 0px 5px #2a3cad;
  position: relative;
}

.content h2{ font-size:19px;}

.box{
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 300px;
  height: 300px;
  background: #111845a6;
  box-sizing: border-box;
  overflow: hidden;
  box-shadow: 0 20px 50px rgb(23, 32, 90);
  border: 2px solid #2a3cad;
  color: white;
  padding: 20px;
}

.box:before{
  content: '';
  position:absolute;
  top:0;
  left:-100%;
  width:100%;
  height:100%;
  background: rgba(255,255,255,0.1);
  transition:0.5s;
  pointer-events: none;
}

.box:hover:before{
  left:-50%;
  transform: skewX(-5deg);
}

.box .content{
  position:absolute;
  top:15px;
  left:15px;
  right:15px;
  bottom:15px;
  border:1px solid #f0a591;
  padding:20px;
  text-align:center;
  box-shadow: 0 5px 10px rgba(9,0,0,0.5);
}

.box span{
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  display: block;
  box-sizing: border-box;
}

.box span:nth-child(1)
{
  transform:rotate(0deg);
}

.box span:nth-child(2)
{
  transform:rotate(90deg);
}

.box span:nth-child(3)
{
  transform:rotate(180deg);
}

.box span:nth-child(4)
{
  transform:rotate(270deg);
}

.box span:before
{
  content: '';
  position: absolute;
  width:100%;
  height: 2px;
  background: #50dfdb;
  animation: animate 4s linear infinite;
}

@keyframes animate {
  0% {
  transform:scaleX(0);
  transform-origin: left;
  }
  50%
  {
    transform:scaleX(1);
  transform-origin: left;
  }
  50.1%
  {
    transform:scaleX(1);
  transform-origin: right;
  }
  100%
  {
    transform:scaleX(0);
  transform-origin: right;
  }
}