Preloader CSS

Animation required:

@keyframes lds-dual-ring {
    0% {
        transform: rotate(0deg);
    }
    100% {
        transform: rotate(360deg);
    }
}

Practical example

button::after {
    content: "";
    display: inline-block;
    width: 18px;
    height: 18px;
    margin: 0 0 0 8px;
    border-radius: 50%;
    border: 3px solid white;
    border-color: white transparent white transparent;
    animation: lds-dual-ring 1.2s linear infinite;
}