Office Small Talk

What constitutes small talk? And how do I navigate office small talk?

I try and say things like hi, hello, good bye, how’s the weather, how was your weekend, etc.

But anything else I try and change the topic or say I’m not comfortable sharing certain things.

For example, one coworker is pretty nosy about trying to find out whether or not I’m in a relationship and I’ve hinted that I’m not in one but the topic is brought up a lot even after the hints.

Is talking about personal relationships a part of small talk? One person talked about politics which I thought was a big nono in the office, but is apparently allowed?