.ramka_bdr {
    position: relative;
    width: 200px;
    height: 200px;
    margin: 30px auto;
    box-sizing: border-box;
    overflow: hidden;
    display: flex;
    align-items: center;
    justify-content: center; 
    font-size: 24px;
    font-family: 'Roboto Condensed', sans-serif;       
}
.ramka_bdr span {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    display: block;
    box-sizing: border-box;
    z-index: -1;
}
.ramka_bdr span:nth-child(1) {
    transform:rotate(0deg);
}
.ramka_bdr span:nth-child(2) {
    transform:rotate(90deg);
}
.ramka_bdr span:nth-child(3) {
    transform:rotate(180deg);
}
.ramka_bdr span:nth-child(4) {
    transform:rotate(270deg);
}
.ramka_bdr span:before {
    content: '';
    position: absolute;
    width:100%;
    height: 6px;
    background: #BFE2FF;
    animation: anim-ramka_bdr 4s linear infinite;
}
@keyframes anim-ramka_bdr {
    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;   
    } 
}