Email Starter Templates render differently on different email clients.
The Marketo Starter Templates are meant to be used as examples. It would not be possible to create a 1-size-fits-all template that works for all email clients. The Starter Templates are provided for a starting place for your web development team to build off the existing HTML, including optimizing it for display on various email clients. Different email clients will have slightly different interpretations of the HTML. An experienced web developer should be able to help you adjust the code to compensate for these differences.