Question

I’m trying to do a sliding door button that can be used in general purpose
everything works fine except the Firefox.
the span element in button always lower 2px in FF.

here is example

http://jsbin.com/orami3/4

Answer 1

Try this:

button::-moz-focus-inner { 
    border: 0;
    padding: 0;
}

(Mind that the colon (:) is doubled, yes.)

The extra padding in this case is caused by an obscure Firefox bug.

(Having encountered this bug myself I’ve found the solution at this blog, via a Google search.)