.site-welcome{
    display: none;
    position: fixed;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    background: #888;
    z-index: 1;
    justify-content: center;
    align-items: center;
}
.site-welcome.active{
    display: flex;
}

.loading{
    width: 200px;
    height: 200px;
    position: relative;
}

.loading::before,
.loading::after{
    content: '';
    width: 0px;
    height: 0px;
    background: #000;
    border-radius: 50%;
    position: absolute;
    left: 0;
    top: 0;
    right: 0;
    bottom: 0;
    margin: auto;
    animation: s 2s linear infinite;
}

.loading::after{
    animation-delay: 1s;
}

@keyframes s{
    0%{
        width: 0;height: 0; opacity:1;
    }
    100%{
        width: 100px;height: 100px; opacity: 0;
    }
}