I have read this question and I am having the same problem:
Put text input inside label for radio button?
Feel free to take a look using Firefox (Chrome and IE8 do not have this problem.):
http://pastehtml.com/view/1dbqqb3.html
I now understand some javascript has to be used to fix this behavior in Firefox.
But I have no idea how to write this piece of codes.
Thanks in advance.
Some html:
The JavaScript: