the.com/details
The small things that quietly decide whether the big thing works.
means The individual small parts, facts, or features that make up something larger and more complete.
from From French detail, meaning a cutting into pieces — from de- (apart) plus tailler (to cut), so a detail is literally a slice carved off the whole.
Devil's addressThe devil is in them; so is God.
Plural mindOften used singular: a detail, an assigned task.
Military slangA detail is also a small assigned squad.