#mainLoader {
     opacity:    1;
     background: #ffffff;
     width:      100%;
     height:     100%;
     z-index:    1000;
     top:        0;
     left:       0;
     position:   fixed;
     display: flex;
     align-items: center;
     justify-content: center;
}
#mainLoader .main-pre-loader {
    /* position: absolute; */
    left: 45%;
    top: 45%;
    border: 16px solid #f3f3f3;
    border-top: 16px solid #848484;
    border-radius: 50%;
    width: 120px;
    height: 120px;
    animation: spin 3s linear infinite;
}

@keyframes spin { 
    from { 
            transform: rotate(0deg); 
    } to { 
            transform: rotate(360deg); 
    }
}