trifle; minor detail
Refers to something small, trivial, or of little importance. Often used in contrast to more significant matters.
Don't get hung up on such a trifle.
細事は後回しにして、大事なことから片付けよう。
Let's put the minor details aside and take care of the important things first.
Compound of 細 (small, fine) and 事 (matter, thing). The exact historical derivation is uncertain, but the meaning is transparent from its components.