.btn{
    position: relative;
}
input:invalid{
    box-shadow: none;
}
.loading-icon {
    border-radius: inherit;
    position: absolute;
    left: 0;
    top: 0;
    bottom: 0;
    right: 0;
    z-index: 10;
    background: #c13a4d;
    content: '<i class="fa fa-spinner fa-spin fa-3x fa-fw"></i>';
    display: flex;
    align-items: center;
    justify-content: center;
}