Resolves all of issue #93240
Reproduces a similar change as #99086, but with improvements
In particular, this PR inlcludes:
* redesigning the crate-search selector so the background color matches its surroundings
* decrease the font of the dropdown menu to a reaonable size
* add a hover effect
* make the color of the arrow theme-dependent, using a surrounding div, with :after pseudo-element
that can then be transformed using CSS filters to approximate the desired color
* fix the text "in" to match the title font
* remove the "for xyz" in the "Results for xyz in [All crates]" title when
searching for search term "xyz"; you can already see what you're searching for
as it's typed in the search bar!
* in line with #99086, handle super-long crate names appropriately without a long <select>
element escaping the screen area; the improvement is that we also keep the title
within a single line now; uses some flex layout shenanigans...
* the margins / paddings are adjusted so the selected label of the <select> fits within
the rest of that title nicely; also some inconsistency in the way that Firefox renders
a <select> with "appearance: none" (roughly 4px more padding left and right of the text
than e.g. Chrome) is worked around, and it now produces a result that looks (essentially)
identical to Chrome
* the color of the help menu and settings menu border in light theme is made to match with
the color of the corresponding buttons, like they do (match) in the ayu theme
* the casing of "All crates" changes to "all crates"
* the new tests from #99086 are temporarily disabled, until they can be adapted later
this change removes some interactive elements in `@media print` form.
more specifically, it removes the source links, the expand/collapse toggle buttons, and the `#copy-path` button.
it also adjusts some spacing and removes the `.top-doc` description completely if it's currently collapsed.
rustdoc: improve click behavior of the source code mobile full-screen "sidebar"
On desktop, if you open the source code sidebar, it stays open even when you move from page to page. It used to do the same thing on mobile, but I think that's stupid. Since the file list fills the entire screen on mobile, and you can't really do anything with the currently selected file other than dismiss the "sidebar" to look at it, it's safe to assume that anybody who clicks a file in that list probably wants the list to go away so they can see it.
Split out separately from #98772
rustdoc: make source sidebar toggle a real button
This fixes tab focus, so that you can open and close the sidebar from keyboard.
This should cause no visible change in appearance at all. The only way you'd know anything different is if you tried to use keyboard controls to open the source code file navigation sidebar.
Separated out from #98772
rustdoc: use <details> tag for the source code sidebar
This fixes the extremely poor accessibility of the old system, making it possible to navigate the sidebar by keyboard, and also implicitly gives the sidebar items the correct ARIA roles.
Split out separately from #98772
Use CSS variables to handle theming
This is the start for our simplification of theming. Considering how big the diff quickly becomes, I think it's better to do it in multiple parts.
(The 3 first commits come from https://github.com/rust-lang/rust/pull/98297 so once it's merged, they'll disappear).
Normally they shouldn't be any UI changes. You can check it [here](https://rustdoc.crud.net/imperio/css-simplification/doc/foo/index.html).
cc `@notriddle`
r? `@jsha`
On desktop, if you open the source code sidebar, it stays open even when you
move from page to page. It used to do the same thing on mobile, but I think
that's stupid. Since the file list fills the entire screen on mobile, and you
can't really do anything with the currently selected file other than dismiss
the "sidebar" to look at it, it's safe to assume that anybody who clicks a
file in that list probably wants the list to go away so they can see it.
This fixes the extremely poor accessibility of the old system, making it
possible to navigate the sidebar by keyboard, and also implicitly gives the
sidebar items the correct ARIA roles.
The source sidebar has a setting to remember whether it should be open or
closed. Previously, this setting was handled in source-script.js, which
is loaded with `defer`, meaning it is often run after the document is rendered.
Since CSS renders the source sidebar as closed by default, changing this
after the initial render results in a relayout.
Instead, handle the setting in storage.js, which is the first script to load
and is the only script that blocks render. This avoids a relayout and means
navigating between files with the sidebar open is faster.
Improve Rustdoc UI for scraped examples with multiline arguments, fix overflow in line numbers
This PR improves a few aspects of the scrape examples feature in Rustdoc.
* Only function names and not the full call expression are highlighted.
* For call-sites with multiline arguments, the minimized code viewer will scroll to the top of the call-site rather than the middle if the argument is larger than the viewer size, ensuring that the function name is visible.
* This fixes an issue where the line numbers column had a visible x-scroll bar.
r? `@GuillaumeGomez`
