You can remove the background but you currently can't remove the border. Next version I'll do something to add the ability for this.

i added some variables that should allow you to do this in v1.1.0, you can add this below all of the imports in the theme file:

:root {
    --essence-app-rounding: 6px;
    --essence-app-padding: 18px;
    /* --essence-app-background-image: none; */ /* uncomment this if you want to remove the background image */
}

to completely remove it just set them to 0px, it has to be 0px otherwise it just won't work properly