Main screen and music replaced.
Place the included 'main' folder inside your Saved Games/DCS.openbeta/MissionEditor/themes folder, and select 'User Theme' inside DCS on Misc Tab.
I have included 4 additional artworks that you can use, just delete the additional text at end of filename and replace 'base-menu-window' file in main folder.
Artwork used found freely available on internet and no licence/copyright information found/available.