Here is the page:
Displayed in FIrefox I see all twelve thumbnails
Displayed in Safari I see only the last three.
I open Safari's Web Inspector and I see the following in the image tag for each 'invisible' image:
style="display: none !important; visibility: hidden !important; opacity: 0 !important; background-position: 200px 269px;"
The three thumbnails that ARE visible do not contain display and visibility attributes in their image tags.