I just finished creating my very first custom theme after torturing myself with sifting through code when I don’t really know the first thing about it. 
It’s not perfect, but it’s a start and maybe someone will enjoy it, too! 
NavyGoldTheme.zip (1.3 MB)
NavyGoldThemeUpdated.zip (1.5 MB) updated version with darker buttons and customisable binder background (like it works with the default theme)