As we all know by now, consistently styling form elements with CSS is virtually impossible. However, with a few tweaks and after reading Firefox’s user-agent CSS file forms.css, I discovered the following: button::-moz-focus-inner, input[type="reset"]::-moz-focus-inner, input[type="button"]::-moz-focus-inner, input[type="submit"]::-moz-focus-inner, input[type="file"] > input[type="button"]::-moz-focus-inner { border:1px dotted transparent; padding:0 2px; } … Firefox uses pseudo-elements within the button elements themselves [...]