wikimedia/mediawiki-extensions-MobileFrontend

.overlay {
    &.overlay-loading {
        display: flex;
        align-items: center;
        justify-content: center;
        background-color: rgba( 255, 255, 255, 0.5 );

        // editor overlay needed to hide header
        .header {
            display: none;
        }
        // Avoid display of scroll bar
        .overlay-content {
            overflow: hidden;
        }
    }
}