.back-container {
    width: 100vw;
    height: 100vh;
    position: fixed;
    top: 0;
    left: 0;
    z-index: -1;
    overflow: hidden;
}

.b-card {
    height: 100px;
    width: 100px;
    border-radius: 15%;
    background: linear-gradient(135deg, rgba(255, 255, 255, 0.03), rgba(255, 255, 255, 0.05));
    position: absolute;
    z-index: -1;
    backdrop-filter: blur(2px);
    -webkit-backdrop-filter: blur(10px);
    border-radius: 10px;
    animation: b-box 10s linear infinite;
}

@keyframes b-box {
    0% {
        top: calc(100% + 120px);
        transform: rotate(520deg);
    }

    100% {
        top: -200px;
        border-radius: 50%;
    }
}