Mac / Firefox and Mac / Chrome behave differently.
When on the Home (formerly known as My Workspace) mouse over the site name for one of the sites you might be selecting.
On Firefox, the background of the site name is white and the text changes to white, therefore making it invisible. If, however, you go to a site, then mouse over the other sites, the text changes to blue, so it is visible. The problem only shows itself if Home is selected.
On Chrome, the background for unselected sites is dark gray, blue for the selected site. Hovering over a site makes it a lighter gray background (which seems okay?). And behaves the same whether home is selected or a site is selected.
Seems like this is a master/12 issue and not an 11 branch issue.