You could always try reinstalling Firefox:
https://www.mozilla.org/en-US/firefox/linux First, make a backup of your profile (assuming it works the same way under Linux) so that you can restore that. Start out with a clean install of the latest Firefox, see if the site runs normally, if yes; restore your profile and see if it still works. If not, there is something in your profile (Add-ons most likely) that is messing up the site.
I just had a look at that site, it is quite image and video heavy, but after a delay in loading it does work here. The mobile version may be a different page or a different layout based on CSS, using fewer or smaller images. That is common these days.