sphinx-copybutton: Using sphinx-copybutton breaks custom layout

First off - very cool package. Thanks for putting it together.

I tried adding sphinx-copybutton to our docs and got some unexpected results. It seems that something in the plugin is messing with the css for our custom bootstrap theme/css.

Left: expected layout without sphinx-copybutton, Right: layout with sphinx-copybutton.

Do you have thoughts on what might be causing this or how to fix it?