Hello,
I live in Switzerland, near Basel. It is very easy for me to go to the station “Basel, Bad. Bh.” which is in Germany. If I want to go to Berlin and other cities in Germany in one month, is it possible for me to buy a one-country ticket for Germany? Or do I need to pay a ticket for multiple countries (since Basel, Bad. Bh. might not be included to the stations that can be used for the interrail ticket)?
And can a one-country ticket be used for all local trains in Germany (= not just the big cities as shown on the map of your website)? For example with city busses?
Best regards and thank you!

but it is the tariff border between SBB and DB. From there, all DB tickets are valid, including Interrail for Germany.