SOURCE

<div class="box">
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    跑马灯边框
</div>

.box{
    width: 200px;
    height: 80px;
    background-color: transparent;
    /* 盒子居中 */
    position: absolute;
    top: 50%;
    margin-top: -40px;
    left: 50%;
    margin-left: -100px;
    /* 文字居中 */
    text-align: center;
    line-height: 80px;
    overflow: hidden;
}
.box :nth-child(1){
    background: linear-gradient(to right, transparent , #0FF);
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 5px;
    animation: run1 1s linear infinite;
}
.box :nth-child(2){
    background: linear-gradient(to bottom, transparent , #0FF);
    position: absolute;
    top: 0;
    left: 195px;
    height: 100%;
    width: 5px;
    animation: run2 1s linear infinite;
    animation-delay: .3s;
}
.box :nth-child(3){
    background: linear-gradient(to left, transparent , #0FF);
    position: absolute;
    top: 75px;
    left: 0;
    width: 100%;
    height: 5px;
    animation: run3 1s linear infinite;
    animation-delay: .6s;   
}
.box :nth-child(4){
    background: linear-gradient(to top, transparent , #0FF);
    position: absolute;
    top: 0;
    left: 0;
    height: 100%;
    width: 5px;
    animation: run4 1s linear infinite;
    animation-delay: .9s;
}
@keyframes run1{
    0%{
        transform: translateX(-400px);
    }
    100%{
        transform: translateX(400px);
    }
}
@keyframes run2{
    0%{
        transform: translateY(-160px);
    }
    100%{
        transform: translateY(160px);
    }
}
@keyframes run3{
    0%{
        transform: translateX(400px);
    }
    100%{
        transform: translateX(-400px);
    }
}
@keyframes run4{
    0%{
        transform: translateY(160px);
    }
    100%{
        transform: translateY(-160px);
    }
}