Webbrowsers that use the Webkit engine (Safari Mobile @ iOS, Google Chrome @ iOS) ignore viewport settings for content that is served from .MOBI domains and render content differently than content that is served from .COM domains!
https://bugs.webkit.org/show_bug.cgi?id=97556
http://www.davidroessli.com/logs/2010/04/safari_ignores_viewport_mobi_domains/
http://blog.planetargon.com/entries/2012/4/17/the-mobile-viewport-short-and-sweet