UPDATED APRIL 14, 2021:
A federal appeals court in California has held that the protections of the ADA do not apply to websites. Its ruling also finds that Title III applies to tangible, physical places. It does not apply to intangible places such as a website. The case is: Gil v. Winn-Dixie Stores, Inc., No. 17-13467 (11th Cir. 4/7/2021). Not all the circuits agree with this result, so SCOTUS will eventually have to look at the matter.