Alice's Adventures in Wonderland has a humorous tone. The third-person narrator speaks sympathetically, but also critically, of the story's events. For example, he employs both sarcasm and euphemism in Chapter 1:
[Alice] had read several nice little stories about children who had got burnt, and eaten up by wild beasts and other unpleasant things, all because they would not remember the simple rules their friends had taught them: such as, that a red-hot poker will burn you if you hold it too long; and that, if you cut your finger very deeply with a knife, it usually bleeds; and she had never forgotten that, if you drink much from a bottle marked “poison,” it is almost certain to disagree with you, sooner or later.
The euphemism about "disagreement" creates a humorous tone around a serious subject. This lets the reader know that Alice is not in serious danger, nor will she be at any point in the story, even when her circumstances seem dire.
The light, clever, humorous tone communicates the narrator's sympathy and intelligence. Having a reliable third-person omniscient narrator helps the reader make sense of an otherwise wild story. Although her return to reality remains uncertain until the final pages, readers do not doubt for a moment that Alice will emerge from her adventures unscathed.