How to get black keyboard layout for Lollipop keyboard?
Your current layout is called "Material Light". To change it, though there isn't a pure black version, go to


  Settings > Language and Input > Google Keyboard > Appearance and Layouts


The dark material setting is called "Material Dark" and looks like this:



I'm assuming you want material design as you are keeping it stock, but there are the old KitKat 'Holo' themes in there also.