.preloader {
    display: -ms-flexbox;
    display: flex;
    background-color: #f4f6f9;
    height: 100vh;
    width: 100%;
    transition: height 200ms linear;
    position: fixed;
    left: 0;
    top: 0;
    z-index: 9999;
  }

.dark-mode .preloader {
background-color: #454d55 !important;
color: #fff;
}