HTMLify

* {
    box-sizing: border-box;
}

body {
    background-color: #161622;
    display: grid;
    place-items: center;
    height: 100vh;
}

.circle-border {
    width: 150px;
    height: 150px;
    padding: 3px;
    border-radius: 50%;
    background: linear-gradient(0deg, rgba(63, 249, 220, 0.1) 33%, rgba(63, 249, 220, 1) 100%);
    animation: spin .8s linear 0s infinite;
}

.circle-core {
    width: 100%;
    height: 100%;
    background-color: #161622;
    border-radius: 50%;
}

@keyframes spin {
    from {
        transform: rotate(0);
    }

    to {
        transform: rotate(359deg);
    }
}