remove 1px empty space in navbar (extremely minor)

[Godsenal]

Hi. First of all, thanks to all contributors of react-query.
This is a super minor issue (may not be an issue at all), so i'm not sure that i can report this.

I'm perusing your docs, but this 1px space getting caught in my eyes..

I think below img makes this space.

https://github.com/tannerlinsley/react-query/blob/4dcb490d4d535fdab65048be92d6e78c4858e2cd/docs/src/pages/_app.js#L51

Maybe we can make this element to absolute position or something?
(I didn't post a PR because this image seems to be used for analytics.)