Precisely in that way, very carefully and appropriately, as in The children had to be dressed just so for their aunt's wedding. [Mid-1700s]
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
How to use just so in a sentence
Apparently, by just-so-happening to love the coolest shows on TV at the time (while still running the country).Obama Loves ‘Breaking Bad’ Because Of Course He Does | Kevin Fallon | December 30, 2013 | THE DAILY BEAST
The mother of two appears topless, in a pair of assless chaps, with her short hair tousled just-so.Nicole Kidman Topless on the Cover of V Magazine's Travel Issue | Isabel Wilkinson | August 22, 2012 | THE DAILY BEAST
I have included only “hero tales, serious and droll,” beast stories and fables, and pourquoi or “just-so” stories.Filipino Popular Tales | Dean S. Fansler
The mind invents what Mr. Kipling would call a "Just-so story" to account for something already there.Anthropology | Robert Marett