Capitalize the title's lowercase word

Warning²Federal courts, Illinois courts21st and 22nd editions

A book's title is capitalized word by word, the word after a colon included; only a short article, conjunction or preposition stays lowercase, unless it opens the title or follows the colon.¹

1. 1R. 8(a) Headings and titles. Tables: R. 15.3 Title.
2. 2A warning: the form is usually wrong under the rule in note 1, and context can justify it.