examples.css

#preloader {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: #3F51B5;
    z-index: 1000;
}
#preloader #preloader-inner {
    display: block;
    position: relative;
    left: 50%;
    top: 50%;
    width: 150px;
    height: 150px;
    margin: -75px 0 0 -75px;
    border-radius: 50%;
    border: 3px solid transparent;
    border-top-color: #e91e63;
    animation: spin 2s linear infinite;
}
#preloader #preloader-inner:before {
    content: "";
    position: absolute;
    top: 5px;
    left: 5px;
    right: 5px;
    bottom: 5px;
    border-radius: 50%;
    border: 3px solid transparent;
    border-top-color: #e91e63;
    animation: spin 3s linear infinite;
}
#preloader #preloader-inner:after {
    content: "";
    position: absolute;
    top: 15px;
    left: 15px;
    right: 15px;
    bottom: 15px;
    border-radius: 50%;
    border: 3px solid transparent;
    border-top-color: #e91e63;
    animation: spin 1.5s linear infinite;
}
@keyframes spin {
    0% {
    transform: rotate(0deg);
}
to {
    transform: rotate(1turn);
}
}