Device preview don't work in Safari

Hi,

I've made the first draft of a new website. I can do a device preview on an iPhone and an iPad when using Chrome or Firefox. But when using Safari I got a blank page. I copied the whole stuff to a test folder on the server and then Safari had no problems at all. Every preview on desktop browsers work (also Safari). So I suspect it a problem with Safari on iOS or a specific device preview problem.

Any ideas?

Ulrich