Highlighted items are hidden in gh-pages API docs

[liamcurry]

Highlighted items are hidden in the Github pages API docs. Tested in Brave and Firefox.

• Example gh-pages URL: https://rustwasm.github.io/wasm-bindgen/api/web_sys/struct.Element.html#method.set_inner_html
• Example docs.rs URL: https://docs.rs/web-sys/0.3.9/web_sys/struct.Element.html#method.set_inner_html

Highlighted items are invisible due this selector in rustdoc.css:

.in-band, code {
    z-index: -5;
}

versus

[fitzgen]

This is a bug in rustdoc. Filed as rust-lang/rust#57712