Use more jQuery to avoid displaying Expand Description more often.

Sometimes (e.g. on Rust CI) the "expand description" text of the
collapse toggle was displayed by default, when a page is first
loaded (even though the description is expanded), because some
Content-Security-Policy settings disable inline CSS.

Setting it the style with the `.css` method allows the output to be used
in more places.
@huonw I think this broke adding the toggles at all :(

See: http://doc.rust-lang.org/std/vec/struct.Vec.html#

CC #17125