simple 2560*1600 desktop wallpaper based on ubuntustudio logo at wiki dot ubuntu dot com slash UbuntuStudio slash Artwork slash UserShowcase. low resolution for small file size. use inkscape with gradients.
matching firefox theme at https://addons.mozilla.org/en-US/firefox/addon/ubuntustudio-before-dark/
matching plymouth splash theme at https://www.opendesktop.org/p/1176481/