IIIF Catalog returned in mime application/ld+json causes download of document (instead of rendering document in browser) for old browsers.
Browser was Firefox
For the catalog page, I am now returning application/json (instead of ld+json). This should resolve the problem for older browsers, if I understand the problem correctly. The info.json and manifest.json are still being served as ld+json as per the IIIF specification (it's less relevant for a human to access those pages directly)
Fixed on commit 20789e1b8d3ac28d779250f11e49880958b14a1a of https://github.com/mekarpeles/iiif.archive.org on master: