At least OSX Safari 5, possibly other Safari versions, are identified by the html5please api as a mobile browser. In addition to html5please's api response coming back with agent.type as "mobile", the generated html to show if the browser is missing a feature also only recommends mobile browsers, since it thinks this browser is a mobile browser:

Please ignore "thalamus" in the image above. We string replace "the page" to "Thalamus" in the returned html for user-friendliness.