When you include ReCaptcha in your code and you find that the textbox which takes the actual answers from the user (#recaptcha_response_field) is aligned perfectly in IE6, IE7 and IE8, but not in firefox you can implement the following to get it fixed.
I played around a bit but found the solution is to include the following before your ReCaptcha loads then it fixes it in firefox and does not break in any of the Internet Explorer versions (tested 6,7 and 8)
Remember this needs to happen BEFORE ReCaptcha loads else it won't work. It is also crucial that you add the !important at the end, else it won't override the default styling.
In your CSS file that loads before ReCaptcha put the following line
If you prefer to do it inline you can paste the following before ReCaptcha loads
I hope this saves you some time, as I could not find any articles on google even referencing this problem. Maybe it's only related to something in my site, but I removed all stylesheets and this problem still existed.