About 30 minutes by tram from Nice city. The tram ...

About 30 minutes by tram from Nice city. The tram was as cheap as 1.5 euros between the city and the airport at a flat rate, so there was no worry about security.
There is still a lot of Japanese information that says "bus or taxi only to the airport", but some airport shuttle buses have already been abolished. I personally think that a tram is fine if you get lost.
The airport itself is not large.