(edit) grammar
"I find your work product to be of consistently adequate quality. I also appreciate that your personal standards for hygiene and attire do not detract in any way from the efficient operation of this office."
It sounds very odd, doesn't it? The HR employee is not the gold standard for advice on how to interact with your co-workers. That person is employed to minimize potential legal liabilities to the company.
The appropriate way to say "you look nice" to a co-worker in a professional setting is to say, "you look nice". You say it in the same way that you would say it to your mother, or to anyone else for which you have both some respect and zero potential for romantic entanglement. If you can reasonably say something to your own mother, you can say it to a female co-worker.
Refusing to acknowledge someone else's positive qualities creates a completely different sort of hostile workplace, especially if that person is at all extroverted. But that sort of hostile workplace does not invite lawsuits.
That said, "good job on fixing that DR so fast" would be a far better compliment.
The reason for this is that clothes are the result of decisions and choices that people make. So, complimenting a piece of clothing is sort of complimenting something a person did.
Whereas, complimenting their overall look (and especially their body) is sort of complimenting something a person is--which most people feel a lot less control over. And, it runs the risk of creating a sense that their body is itself an object to be considered and critiqued.