Plugin and theme icons cannot be displayed

Hello

I have a problem concerning the icons of plugins and the icons of WordPress themes. When i visit my Website with Google Chrome or Internet Explorer I don’t see the logo of the Jetpack Plugin or the social media icons from my theme. Only to name two examples. However in Safari everything looks fine.

I mad two screenshots to show the mistake.

https://andrinunterwegs.ch/wp-content/uploads/2016/04/Groundhopping-since-2013-%E2%80%BA-Andrin-unterwegs-2016-04-06-10-26-59.png

https://andrinunterwegs.ch/wp-content/uploads/2016/04/Dashboard-%E2%80%B9-Andrin-unterwegs-%E2%80%94-WordPress-2016-04-06-10-27-27.png

The URL of the Blog is: https://www.andrinunterwegs.ch/?theme=kerinci

Has anybody an idea what is causing the problem and how to solve it?

Thanks for your help it it’s highly appreciated.

Cheers

Luigi