I have read this sentence:
"No matter how many tools a writer uses to detect errors, some always creep in and these often leap off the page for a fresh reader."
what does that phrase "Leap Off the page" mean?
When something 'leaps off the page' it is so obvious that it catches the readers attention immediately. In your example, the errors are so blatant that they cannot be missed!
This bold print 'leaps off the page' because you cannot ignore its presence!