一丝不苟 (一絲不苟) yī sī bù gǒu

yī sī bù gǒu set phrase not the least bit careless; meticulous
Domain: Idiom 成语
Notes: (CC-CEDICT '一絲不苟'; CCI '一絲不苟', p. 46; Guoyu '一絲不苟')