wearing light clothes for style; dressing lightly to look fashionable
A set phrase describing someone who wears thin or insufficient clothing in cold weather out of vanity or a desire to appear stylish. Often used critically or humorously.
Not even wearing a coat in the middle of winter—that's taking 'fashion over warmth' too far.
彼女は伊達の薄着で、寒そうに震えていた。
She was dressed lightly for the sake of fashion and was shivering in the cold.