Remove extra button spacing/padding in Firefox

Solution 1:

Add this:

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

http://jsfiddle.net/thirtydot/Z2BMK/1/

Including the border rule above is necessary for buttons to look the same in both browsers, but also it removes the dotted outline when the button is active in Firefox. Lots of developers get rid of this dotted outline, optionally replacing it with something more visually friendly.

Solution 2:

To fix it on input elements as well add

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

is simple perfect!