Is it grammatically correct to start this phrase with "how"?

"How closely our interests align may surprise you."

Is it grammatically correct to start this phrase with "how"? If not, what rule makes that so? Is there a better way to say this? Thanks for any input!


The sentence itself is grammatically correct. In this use, how is an adverb, not a conjunction, describing the degree of closeness, and it is perfectly acceptable to begin a phrase with an adverb. For example: Even camels need to drink.