Problem on smartphone since a few days

Today I noticed my site is not responsive/displaying well on smartphones, like Iphone. This was not yet the case last week. No clue what happened. All looks fine on computer.

Additional info: The only “large” change I made was adding the “insert headers and footers” plugin, so I could easily add the google analytics scripts.
If there is a better way I can add this to each page and post. I can delete the plugin and see if that caused the problem.

I already fixed a large part of it, by deactivating the Mobile-Function in Jetpack. Now the site is still only partially responsive in portrait-mode on smartphones.

Hi, this article can be helpfull for add your analytics code direct to your template without any thirdpart extension. If there will be still responsiveness problem please let us know