The table of contents doesn't sync with the actual navigation in the "Performance & optimization" section, apart from the "Overview" section. If you select any other page, then that page shows — but the table of contents jumps back to "Overview".
Below you can see the "Rendering performance / Performance best practices" section shown, but only "Overview" is highlighted on the page:
I recorded a video of this behavior.
The error shows in macOS Catalina 10.15.2 with Safari 13.0.4, Chrome 79.0.3945.88, and Firefox 71.
The table of contents doesn't sync with the actual navigation in the "Performance & optimization" section, apart from the "Overview" section. If you select any other page, then that page shows — but the table of contents jumps back to "Overview".
Below you can see the "Rendering performance / Performance best practices" section shown, but only "Overview" is highlighted on the page:
I recorded a video of this behavior.
The error shows in macOS Catalina 10.15.2 with Safari 13.0.4, Chrome 79.0.3945.88, and Firefox 71.