Steam Store pages not working in Safari browser

[VanillaBaron]

When I visit a product page (all of them, but for example, say Euro Truck Sim 2) the screenshot/video section does not work. I cannot scroll using the arrows or the scrollbar, or get an enlarged view by clicking on a screenshot, and although the screenshot thumbnails load, the screenshots themselves do not even if I click a thumbnail.

I cannot see the MacOSX System requirements because that little tab in that section won't display when I click on the tab heading (though the cursor does change to the 'hand' cursor indicating a link or onclick is recognised.)

I have trouble getting the reviews to load also; sometimes they do, sometimes not, sometimes I have to mess with the filters even though the defaults should be showing all the English reviews. This is less of an issue for me than the screenshots.

I have ensured that adblock and no-track extensions are disabled and that Flash is enabled (although I don't think the site uses Flash?)

MacOS X 10.9.5 Mavericks and Safari 9.1.3 (9537.86.7.8)

Not sure how long it was since my last visit when store pages worked, maybe a few weeks?