This adds labels to the icons and moves them away from the search box.
These changes are made together, because they work together, but are based on
several complaints:
* The [+/-] thing are a Reddit-ism. They don't look like buttons, but look
like syntax
<https://rust-lang.zulipchat.com/#narrow/stream/266220-t-rustdoc/topic/More.20visual.20difference.20for.20the.20.2B.2F-.20.20Icons>,
<https://github.com/rust-lang/rust/issues/59851>
(some of these are laundry lists with more suggestions, but they all
mention [+/-] looking wrong)
* The settings, help, and summary buttons are also too hard to recognize
<https://lwn.net/Articles/987070/>,
<https://github.com/rust-lang/rust/issues/90310>,
<https://github.com/rust-lang/rust/issues/14475#issuecomment-274241997>,
<https://internals.rust-lang.org/t/improve-rustdoc-design/12758>
("Not all functionality is self-explanatory, for example the [+] button in
the top right corner, the theme picker or the settings button.")
The toggle-all and toggle-individual buttons both need done at once, since we
want them to look like they go together. This changes them from both being
[+/-] to both being arrows.
Settings and Help are also migrated, so that the whole group can benefit from
being described using actual words.
Additionally, the Help button is only shown on SERPs, not all the time.
This is done for two major reasons:
* Most of what's in there is search-related. The things that aren't are
keyboard commands, and the search box tells you about that anyway.
Pressing <kbd>?</kbd> will temporarily show the button and its popover.
* I'm trading it off by showing the help button, even on mobile.
It's useful since you can use the search engine suggestions there.
* The three buttons were causing line wrapping on too many desktop layouts.
This was added to control percentage sizes, in
79956b96e8
Now, the only percentage size is [`border-radius`], which is
based on the size of the box itself, not its containing block.
This leaves the property unused.
[`border-radius`]: https://developer.mozilla.org/en-US/docs/Web/CSS/border-radius
This code was added in 9dc5dfb975
and 704050da23 because the browser-
native checkbox was `display: none`, breaking native keyboard
accessibility.
The native checkbox is now merely `appearance: none`, which does
not turn off [behavior semantics], so JavaScript to
reimplement it isn't needed any more.
[behavior semantics]: https://w3c.github.io/csswg-drafts/css-ui/#appearance-semantics
This is very dependent on subjectivity and what screen you use,
but this change makes the radio buttons' outer circle less ugly.
This is because I could see the pixels very clearly, thanks to the
very thin line and high contrast. This change makes both less
severe, giving your browser's antialiasing algorithm more to
work with. Since it's thicker, lowering the contrast shouldn't
impact visibility.
* Changes the class names so that they all start with `setting-`.
That should make it harder to accidentally use a setting class outside
the settings popover, where loading the CSS might accidentally change
the styles of something unrelated.
* Get rid of an unnecessary wrapper DIV around the radio button line.
* Simplify CSS selectors by making the DOM easier and more intuitive
to target.
rustdoc: remove redundant CSS rule `#settings .setting-line`
Since the current version of settings.js always nests things below a div with ID `settings`, this rule always overrode the one above.
This prevents some strange blur-event-related bugs with the "?" command
by ensuring that the focus remains in the same spot when the settings
area closes.
