After upgrade from Sydney to Sydney Pro it doesn't fit in a mobile phone displ

I have created a new WP-site with SYDNEY and it fits perfect in in my LUMIA 650.
After an Upgrade lots of Settings have been deletet. I have entered again.
After this it still fits in the Lumia-Display perfectly, but just for a second. Then it zooms for about 5%, so it doen’t fit anymore and the last letters are cut off.

Hello Michael,

Can you please provide a link to your website in order to let me inspect it?

Kind Regards, Roman.