.ajax-content-block {
    border-radius: .6rem;
    background: #e3e3e3;
    animation-name: ajax-content-loading;
    animation-duration: 2s;
    animation-iteration-count: infinite;
}

@keyframes ajax-content-loading {
    0%   {background-color: #e3e3e3;}
    50%  {background-color: #f1f1f1;}
    100%   {background-color: #e3e3e3;}
}