.rgbborder {
    position: relative;
}

.rgbborder .itemBig {
    z-index: 1;

}

.rgbborder:before, .rgbborder:after {
    content: '';
    position: absolute;
    left: -2px;
    top: -2px;
    background: linear-gradient(45deg, #fb0094, #0000ff, #00ff00,#ffff00, #ff0000, #fb0094, #0000ff, #00ff00,#ffff00, #ff0000);
    background-size: 400%;
    width: calc(100% + 4px);
    height: calc(100% + 4px);
    z-index: 0;
    animation: steam 20s linear infinite;
}

@keyframes steam {
    0% {
        background-position: 0 0;
    }

    50% {
        background-position: 400% 0;
    }

    100% {
        background-position: 0 0;
    }
}

.rgbborder:after {
    filter: blur(10px);
}