.loader {
    width: 48px;
    height: 48px;
    border-radius: 50%;
    border-top: 3px solid #000;
    border-right: 3px solid transparent;
    box-sizing: border-box;
    animation: rotation 1s linear infinite;
    margin: 0 auto;
}

@keyframes rotation {
    0% {
        transform: rotate(0deg);
    }
    100% {
        transform: rotate(360deg);
    }
}

.loader-hidden
{
    display: none;
}

.loader-visible
{
    display: block;
}