All 3 Uses

nevertheless
in
The Veldt
(Edited)

"He's a wise one for ten. That I.Q. of his —"
"Nevertheless—"
p. 13.3

nevertheless = despite that (used to connect contrasting ideas)
"They've been acting funny ever since you forbade them to take the rocket to New York a few months ago."
"They're not old enough to do that alone, I explained."
"Nevertheless, I've noticed they've been decidedly cool toward us since."
p. 17.1 *
George, you'll have to change your life. Like too many others, you've built it around creature comforts. Why, you'd starve tomorrow if something went wrong in your kitchen. You wouldn't know how to tap an egg. Nevertheless, turn everything off. Start new.

p. 22.6

nevertheless = even so (used to connect contrasting ideas)

Definitions:

(1) (nevertheless)
despite that

Based on idea 1 we might not expect idea 2, but this is a way of saying that even though idea 1 was just stated, we still have idea 2. Synonyms include in spite of that, despite that, nevertheless, nonetheless, on the other hand, in contrast and but.
(2) (meaning too rare to warrant focus)