SOURCE

<div class="container">
  jikesn
</div>

html {
    height: 100%;
    width: 100%;
}

body {
    display: flex;
    align-items: center;
    justify-content: center;
    height: 100%;
    width: 100%;
    overflow: hidden;
    background-color: #1b2431;
}

.container {
    width: 20vw;
    background-color: #1b2431;
    height: 20vw;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 50%;
    font-size: 2rem;
    color: white;
    font-family: roboto;
    font-weight: bold;
    position: relative;
}

.container::before,
.container::after {
    position: absolute;
    content: "";
    top: -5%;
    left: -5%;
    height: 110%;
    width: 110%;
    border-radius: 50%;
    opacity: 0.5;
    filter: blur(60px);
}

.container::after {
    background-color: #00ffff;
    z-index: -1;
    animation: backglow2 15s ease infinite;
}

.container::before {
    background-color: #ff0072;
    z-index: -2;
    animation: backglow1 15s ease infinite;
}

@keyframes backglow1 {
    0% {
        transform: translate(10%, 10%) scale(1);
        opacity: 0.5;
    }
    25% {
        transform: translate(-10%, 10%) scale(0.8);
        opacity: 0.5;
    }
    50% {
        transform: translate(-10%, -10%) scale(1.2);
        opacity: 0.8;
    }
    75% {
        transform: translate(10%, -10%) scale(1.1);
        opacity: 0.2;
    }
    100% {
        transform: translate(10%, 10%) scale(1);
        opacity: 0.5;
    }
}

@keyframes backglow2 {
    0% {
        transform: translate(-10%, -10%) scale(1);
        opacity: 0.5;
    }
    25% {
        transform: translate(10%, -10%) scale(0.8);
        opacity: 0.5;
    }
    50% {
        transform: translate(10%, 10%) scale(1.2);
        opacity: 0.8;
    }
    75% {
        transform: translate(-10%, 10%) scale(1.1);
        opacity: 0.2;
    }
    100% {
        transform: translate(-10%, -10%) scale(1);
        opacity: 0.5;
    }
}