Input box renders oddly in Firefox (offending CSS block identified)

Created by: jml6m

Here is a JSFiddle (open in Firefox): http://jsfiddle.net/aLaXs/

Notice the odd, ugly shadowing effect that's applied only in Firefox browsers. Offending CSS block is this:

button, input, select[multiple], textarea {
    background-image: none;
}

By disabling this effect using Firebug or similar software, the text box looks normal again. Is there a workaround for this? I'm trying to add other attributes to my style.css to counteract this effect, but nothing seems to be working. I've tried adding:

//in style.css
input {
    outline: 0;
    border: 0;
    background-image: initial;
}

None of them has worked. Text box looks normal in other browsers.