[NTG-context] Wiki problem - labels missing from the main diagram on the Page Layout page

When I go to the page layout page on the Contextgarden wiki https://wiki.contextgarden.net/Page_Layout the "typesetting areas" diagram is missing its text labels. If I click on the diagram the Wiki takes me to the underlying layout.svg file and then I /do/ see the labels. This happens in both Safari and Firefox. Any suggestions as to what needs to be changed to get the diagram to display correctly? — Bruce Horrocks Hampshire, UK