Firefox: Remove dotted border from focused buttons

The following Sass will do the trick:

Copybutton,
input[type="reset"],
input[type="button"],
input[type="submit"],
input[type="file"] > input[type="button"]
  &::-moz-focus-inner
    border: none

There's also a plain CSS version Show archive.org snapshot .

Note that you can no longer visually navigate through a form with the keyboard without these borders.