Problem with rendering documentation websites

Following the installation instructions I noticed, by default the ubuntu instructions are displayed, but if you click any other OS (for example, click "CentOS notranslate"), the instructions disappear, and you cannot make the instructions reappear.

The problem has been replicated in the latest Chrome (71.0.3578.98) and Firefox (64.0) on the latest Mac OSX (10.14.2) and also the latest Chrome (71.0.3578.98) and Firefox (64.0) on the latest Windows 10.

The source code for the page is located here, and appears to be correct.

The problem seems to be something in the rendering from markdown to html and/or js.