Learn Danish: Jeg synes at du er lige lovlig nysgerrig. - I think that you are a bit too curious.

Lige lovlig is a fixed idiomatic phrase placed before an adjective to mean "a bit too" or "a little overly." It acts as a degree modifier that softens the adjective. Here, instead of a blunt accusation, it makes the statement "you are a bit too curious."

Why not just say "du er for nysgerrig"?

You can say du er for nysgerrig (you are too curious), but it sounds very direct and potentially harsh. Using lige lovlig cushions the blow. It is a classic Danish way to understate a negative trait, making the criticism sound more polite, conversational, or even slightly humorous.

Doesn't "lovlig" normally mean "legal" or "lawful"? How does it fit here?

Yes, as an adjective on its own, lovlig means "legal." However, when used as an adverb—especially in the cluster lige lovlig—it loses its literal meaning entirely and translates to "rather" or "a bit." You just have to treat lige lovlig as a set phrase where the original definitions of the individual words no longer apply.

Why is "synes" used here for "think" instead of "tror"?

You use synes here because you are expressing a subjective, personal opinion based on your own direct observation of the person's behavior. If you used tror, it would mean you are guessing about a fact you aren't entirely sure of (e.g., "I believe/guess you are curious"), which doesn't fit a direct personal judgment like this.