Button in showcase

Hi there,
I did the Inheritance and I am now wondering about, where I can change the design and place of the button in showcase. I tried alot, including changing and compiling the _showcase.scss and copying the button-css files into .custom.scss. Where is my error in reasoning.

Things I would like to change:

  1. background color/transparency of the button
  2. position should be a little more down

I think a picture is worth a thousand words here. Really you just need to use your inspector in the browser. The source maps from the scss shows you exactly what and where the CSS is coming from: