css实现虚线边框滚动效果的实例代码

<div class="box">
  <p>测试测试</p>
</div>

.box {
  width: 100px;
  height: 100px;
  position: relative;
  background: url(https://www.zhangxinxu.com/study/image/selection.gif);
  p {
    position: absolute;
    left: 0;
    top: 0;
    right: 0;
    bottom: 0;
    margin: auto;
    height: calc(100% - 2px);
    width: calc(100% - 2px);
    background-color: #fff;
  }
}

.box {
  width: 100px;
  height: 100px;
  background: repeating-linear-gradient(
    135deg,
    transparent,
    transparent 4px,
    #000 4px,
    #000 8px
  );
  overflow: hidden;                // 新建一个BFC，解决margin在垂直方向上折叠的问题
  animation: move 1s infinite linear;
  p {
    height: calc(100% - 2px);
    margin: 1px;
    background-color: #fff;
  }
}
@keyframes move {
  from {
    background-position: -1px;
  }
  to {
    background-position: -12px;
  }
}

.box {
  width: 100px;
  height: 100px;
  background: linear-gradient(0deg, transparent 6px, #e60a0a 6px) repeat-y,
    linear-gradient(0deg, transparent 50%, #0f0ae8 0) repeat-y,
    linear-gradient(90deg, transparent 50%, #09f32f 0) repeat-x,
    linear-gradient(90deg, transparent 50%, #fad648 0) repeat-x;
  background-size: 1px 12px, 1px 12px, 12px 1px, 12px 1px;
  background-position: 0 0, 100% 0, 0 0, 0 100%;
  animation: move2 1s infinite linear;
  p {
    margin: 1px;
  }
}
@keyframes move2 {
  from {
  }
  to {
    background-position: 0 -12px, 100% 12px, 12px 0, -12px 100%;
  }
}

.box {
  width: 100px;
  height: 100px;
  background: linear-gradient(0deg, #f0e, #fe0);
  -webkit-mask: linear-gradient(0deg, transparent 6px, #e60a0a 6px) repeat-y,
    linear-gradient(0deg, transparent 50%, #0f0ae8 0) repeat-y,
    linear-gradient(90deg, transparent 50%, #09f32f 0) repeat-x,
    linear-gradient(90deg, transparent 50%, #fad648 0) repeat-x,
    linear-gradient(0deg, #fff, #fff) no-repeat;        // 这里不透明颜色随便写哦
  -webkit-mask-size: 1px 12px, 1px 12px, 12px 1px, 12px 1px, 98px 98px;
  -webkit-mask-position: 0 0, 100% 0, 0 0, 0 100%, 1px 1px;
  overflow: hidden;
  animation: move3 1s infinite linear;
  p {
    height: calc(100% - 2px);
    margin: 1px;
    background-color: #fff;
  }
}
@keyframes move3 {
  from {
  }
  to {
    -webkit-mask-position: 0 -12px, 100% 12px, 12px 0, -12px 100%, 1px 1px;
  }
}