Rollup merge of #104896 - notriddle:notriddle/tooltip, r=GuillaumeGomez

rustdoc: fix broken tooltip CSS

text `#ffffff` on background `#fdffd3` fails the [WCAG color contrast checker], and seems like a mistake in https://github.com/rust-lang/rust/commit/16b55903ee16503e7026677c169727d1907704c2.

Making the cursor a pointer is misleading, since clicking it doesn't do anything.

[WCAG color contrast checker]: https://accessibleweb.com/color-contrast-checker/