.preloader {
    position: fixed;
    top: 0;
    right: 0;
    bottom: 0;
    left: 0;
    background-color: #111;
    transform-origin: bottom;
    z-index: 111111;
}

.preloader .black_wall {
    height: 100%;
    background-color: #222;
    transform-origin: top;
    animation: preloader_slide 0.7s ease-in-out 0s 1 normal both;
}

.preloader .loader {
    width: 100%;
    height: 3px;
    position: absolute;
    border-radius: 2px;
    top: 0;
    right: 0;
    left: 0;
    margin: auto;
    background-color: #FFC41F;
    transform-origin: left;
    animation: loader_running 4s ease-in-out 1s infinite normal both;
}

.preloader.off {
    animation: preloader_slide 0.7s ease-in-out 0s 1 reverse both;
}

@keyframes loader_running {
    0% {
        transform: scaleX(0);
        transform-origin: left;
    }

    49% {
        transform: scaleX(1);
        transform-origin: left;
    }

    50% {
        transform: scaleX(1);
        transform-origin: right;
    }

    100% {
        transform: scaleX(0);
        transform-origin: right;
    }
}

@keyframes preloader_slide {
    from {
        transform: scaleY(0);
    }

    to {
        transform: scaleY(1);
    }
}