nginx-proxy-manager/src/frontend/scss/styles.scss

@import "~tabler-ui/dist/assets/css/dashboard";
@import "tabler-extra";
@import "custom";

/* Before any JS content is loaded */
#app > .loader, #login > .loader, .container > .loader {
    position: absolute;
    left: 49%;
    top: 40%;
    display: block;
}

.no-js-warning {
    margin-top: 100px;
}