loader.css

/* loading */

#loader-wrapper {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 99;
}

#loader {
    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: #5490ea;
    animation: spin 2s linear infinite;
    z-index: 999;
}

#loader:before {
    content: "";
    position: absolute;
    top: 5px;
    left: 5px;
    right: 5px;
    bottom: 5px;
    border-radius: 50%;
    border: 3px solid transparent;
    border-top-color: #5490ea;
    animation: spin 3s linear infinite;
}

#loader:after {
    content: "";
    position: absolute;
    top: 15px;
    left: 15px;
    right: 15px;
    bottom: 15px;
    border-radius: 50%;
    border: 3px solid transparent;
    border-top-color: #5490ea;
    animation: spin 1.5s linear infinite;
}

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

#loader-wrapper .loader-section {
    position: fixed;
    top: 0;
    width: 51%;
    height: 100%;
    transform: translateX(0);
}

#loader-wrapper .loader-section.section-left {
    left: 0;
}

#loader-wrapper .loader-section.section-right {
    right: 0;
}

/* Loaded */

.loaded #loader {
    opacity: 0;
    transition: all 0.3s ease-out;
}

.loaded #loader-wrapper {
    visibility: hidden;
    transform: translateY(-100%);
    transition: all 0.3s 1s ease-out;
}

.loaded #loader-wrapper .loader-section.section-left {
    transform: translateX(-100%);
    transition: all 0.7s 0.3s cubic-bezier(0.645, 0.045, 0.355, 1.000);
}

.loaded #loader-wrapper .loader-section.section-right {
    transform: translateX(100%);
    transition: all 0.7s 0.3s cubic-bezier(0.645, 0.045, 0.355, 1.000);
}