The website and many (if not all) of its subpages should be accessible via the Wayback Machine (archive.org). Simply enter the desired page into the search bar and pick a relevant snapshot of the page.
The linked answer points to the vibrational spectrum of water. The original link is dead, but the most recent snapshot (Nov 2020) is accessible here and seems to be quite a faithful reproduction: for example, it has all the images attached in the answer.
(This is a very general tool which can be used to fix broken links or find information that has otherwise gone missing.)