html::before {
    content: 'Loading';
    position: relative;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    width: 100%;
    height: 105vh;
    text-align: center;
    color: #fff;
    background-color: #333;
    margin-bottom: 10px;
    overflow: hidden;
    z-index: 99;
}
html::after {
    content: '';
    position: absolute;
    top: 0;
    right: 0;
    bottom: 0;
    left: 0;
    transform: translateX(-100%);
    background-image: linear-gradient(90deg,
        rgba(0, 0, 0, 0) 0,
        rgba(0, 0, 0, 0.2) 20%,
        rgba(0, 0, 0, 0.5) 60%,
        rgba(0, 0, 0, 0)
    );
    animation: shimmer 3s infinite;
    z-index: 99;
}
@keyframes shimmer {
    100% {
        transform: translateX(100%);
    }
}