taru-adjective, adverb taking the 'to' particle
Formal, literary term used as a 'taru' adjective or adverb with と, meaning something is of little importance or very small in degree. Rare in modern Japanese.
些々たる問題に過ぎない。
It is nothing more than a trivial matter.
彼は些々たることで怒るような人ではない。
He is not the kind of person to get angry over trifling things.
些細 is the common modern word for 'trivial' or 'minor', used as a na-adjective. 些々 is a rare literary synonym.
Reduplication of 些 (さ, 'a little'), forming a literary term meaning 'trifling' or 'slight'. The exact historical derivation is uncertain.