RHEL 8 docs, table of contents missing?

The RHEL8 docs used to have a TOC on the left so you could quickly browse to each topic.

Using firewalld as an example, the TOC would show 7.1, 7.2 etc, on the left, but now all I see is content pane with one scroll bar for the whole page?

https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/8/html/securing_networks/using-and-configuring-firewalld_securing-networks