: Thicker books require deeper gutters (wider margins) because the bulk of the pages prevents the book from opening flat.
Gutter highlights how-to - Technical Support - Sublime Forum GUTTERING
In publishing and design, the is the crucial extra space added to the inside margin of a layout to account for binding. 📖 The "Gutter" in Text & Publishing : Thicker books require deeper gutters (wider margins)
Beyond physical books, the term is used in digital layouts to manage "white space." GUTTERING
The gutter ensures that text doesn't disappear into the "fold" (the spine) of a bound document.