<div class="loader">
  <span></span>
  <span></span>
  <span></span>
  <span></span>
</div>

body {
    background-color: #000c18;
    margin: 0;
    padding: 0;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
}
.loader {
    position: relative;
    width: 100px;
    height: 100px;
    background: linear-gradient(yellow, green, red, #f7ba14, white);
    border-radius: 50%;
}
.loader span {
    position: absolute;
    width: 100%;
    height: 100%;
    background: linear-gradient(yellow, green, red, #f7ba14, white);
    border-radius: 50%;
    animation: spin 1s infinite linear;
}
@keyframes spin {
    from {
        transform: rotate(0deg);
    }
    to {
        transform: rotate(360deg);
    }
}
.loader span:nth-child(1) {
    filter: blur(5px);
}
.loader span:nth-child(2) {
    filter: blur(20px);
}
.loader span:nth-child(3) {
    filter: blur(45px);
}
.loader span:nth-child(4) {
    filter: blur(50px);
}
.loader::after {
    content: '';
    position: absolute;
    top: 10px;
    left: 10px;
    right: 10px;
    bottom: 10px;
    background-color: #000c18;
    border-radius: 50%;
}