I have custom-made web fonts used on my site. To style my rendering output, I used the following code:
//-webkit-text
Adding
font-weight: normal;
To your @font-face fonts will fix the bold appearance in Firefox.
I found the solution with this link : http://pixelsvsbytes.com/blog/2013/02/nice-web-fonts-for-every-browser/
Step by step method :
apt-get install ttfautohint
):ttfautohint --strong-stem-width=g neosansstd-black.ttf neosansstd-black.changed.ttf
I hope this will help.