#preloader {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: #fff;
    z-index: 9999;
}

.loader {
    border: 6px solid #f3f3f3;
    border-top: 6px solid #3498db;
    border-radius: 50%;
    width: 40px;
    height: 40px;
    animation: preloader linear;
    animation-duration: 4s;
    animation-iteration-count: infinite;
    margin: auto;
    position: absolute;
    top: 0;
    left: 0;
    bottom: 0;
    right: 0;
}

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