html - max-width doesn't work on img on firefox -

i'm making website (http://emosistemas.com/web/) have problem "max-width" in images.

in google chrome works fine, but, in firefox (in responsive mode) doesn't resize it.

the images fails are:

• the image under "inicio"
• the 3 images under "inicio" image

in responsive mobile (less 500px aprox), last 3 images works fine because have "width:100%".

i try transform block, inline-block, position relative, specify widht:auto... works.

i'm using firefox 41.0 , last nightly version.

thanks.

edit:

full screen (works ok): http://i.stack.imgur.com/xinaq.jpg

responsive mode (the images don't resize it): http://i.stack.imgur.com/tevkg.jpg