css实现hover边框动画

  <div class="btn-container">
    <div class="button">
      <div class="button__content">hover me to change</div>
    </div>
  </div>

.btn-container {
    
    
  padding: 10px;
  .button {
    
    
    width: 200px;
    height: 60px;
    position: relative;
    background: #fff;
    margin: 30px auto;
    box-sizing: border-box;
    cursor: pointer;
    text-align: center;
    line-height: 60px;
    &::before {
    
    
      content: "";
      width: 0;
      height: 0;
      background: #00adb5;
      position: absolute;
      top: -1px;
      right: -1px;
      z-index: 0;
      transition: width 0.5s, height 0.5s;
    }
    &::after {
    
    
      content: "";
      width: 0;
      height: 0;
      background: #00adb5;
      position: absolute;
      bottom: -1px;
      left: -1px;
      z-index: 0;
      transition: width 0.5s, height 0.5s;
    }
    &:hover::before {
    
    
      width: calc(100% + 2px);
      height: calc(100% + 2px);
    }
    &:hover::after {
    
    
      width: calc(100% + 2px);
      height: calc(100% + 2px);
    }

    .button__content {
    
    
      height: 100%;
      width: 100%;
      position: absolute;
      left: 0;
      top: 0;
      z-index: 1;
      background: #fff;
    }
  }
}