Size includes everything. Usually the textures are procedural, but can be seeded so they're the same every time. Music is usually pretty easy to encode if it's a chiptune, loads of redundant data.
Hopefully you see this, unfortunately your comment is dead.
Because I think your comment has value I will quote it here, please let me know if you'd like it removed.
"You can also have procedural music.
Viznut (a legendary Finnish democoder) did some experiments to see how short you could code something that still sounds at least interesting:
https://www.youtube.com/watch?v=GtQdIYUtAHg
I also wrote piece of JavaScript that can play these programs in case you want to try create your own: http://www.bemmu.com/music/index.html "