jitsi-meet/css/_notifications.scss

.notification-appear, .notification-enter {
    opacity: 0;
    position: relative;
    left: -200px;
    transition: all .2s !important; // !important needed to overwrite atlaskit default style

    &-active {
        opacity: 1;
        left: 0;
    }
}

.notification-exit {
    opacity: 1;
    position: relative;
    left: 0;
    transition: all .2s !important; // !important needed to overwrite atlaskit default style

    &-active {
        opacity: 0;
        left: -200px;
    }
}