Zoom in/out in html-Pages

I added a html page to my moodle course. If i open it in the mobile/app it is not possible to zoom in or out. 

Most of the page is outside of the view of the app. 

Also it is not possible to move the page left/right you to see all the missing content of the page.

Moving up and down is possible.

Thanks a lot for all the work you have done!