I did that to a coworker on her vaca pics in Cancun and she stopped talking to me. So yeah, its sexual.

A 17 y/o is legally an adult

17 isn't a child.

17 is legally an adult? cannot vote, in federal elections, but can work, can live independently, is considered old enough to consent, drop out of school, and work full time, cannot be drafted, but can enlist. Maybe the phrase, “looks grown up” would be less “offensive” ? ppl
Are so reactive in today’s world; WTF
The president calls a young teenager very attractive, and says he’d be DTF for his own daughter, if things were “different” more than half of ppl don’t care, but you call a legally able to consent “almost adult” good looking and you get yelled at? This is the world with a pedophile as president
The 17 y/ o would need to be emancipated? And legally can be

The only concern is if you hold a position of authority for that “almost adult”
“Positions of Authority: Even where a 17-year-old has reached the legal age of consent, laws generally prohibit sexual activity if the older partner holds a position of trust, dependency, or formal authority over the minor.”
But certainly a complement isn’t of any concern.
“Hey nice outfit!” Isn’t inappropriate.

Try for more tactful

That’s exactly what you did and it’s gross.

Are you SomeMichGuy?

Really??

But sexualizing is exactly what it is. You are not only saying that she is sexy to you, you are saying that’s the way she earns her oxygen, being attractive to you. How about “smart,” “talented,” or “creative,” or any of many qualities she may have. You are telling her and anyone in earshot, that you SEE her as sexual and only sexual. And you’re telling us that’s not what you meant. Not very credible.

17 year old is not a child, still it's a minor and considering your age, it was inappropriate.

A non-sexual compliment could probably have accomplished that much better.
Grown men say inappropriate things to young girls not realizing that for many it just makes them uncomfortable. 🥺

Don’t worry about it. 1 in every 3 SWer is a pedophile and nobody bats an eyelid.