This way we simplify the HTML and generating similar menus will be
easier. We also improve the experience for screen reader users, who
might have been hearing the icons as text because we weren't using the
`aria-hidden` attribute.
We're still keeping the "icon-" classes for compatibility with CONSUL
installations which might have changed this code.
While Foundations's off-canvas menu allows us to forget about writing
CSS, it also leads to complicated HTML.
Ideally Foundation would provide an easy way to simplify what we're
doing, but I haven't found anything in the documentation.
We could simplify the HTML a bit more if we used a CSS grid layout
instead of a flex one, but old browsers have better support for the
latter.
Note we're using `breakpoint(medium)` so we can group the CSS for small
screens and follow SCSS-Lint rules at the same time.
Also note behavior of the main area when the menu appears on small
screens is slightly different: it doesn't move the main content to the
right. I've done it this way so we don't have any overflow issues,
unlike the previous version.
There's a small issue using a label and a checkbox to enable/disable the
menu: sighted keyboard users with a small screen might not be able to
enable the menu. So we're adding the `:focus-within` pseudoclass so the
menu can be normally navigated using the keyboard. Even if old browsers
don't support this pseudoclass, we believe the probability of a sighted
user using a small screen, navigating with the keyboard and using an old
browser is really low, particularly in the admin area.
We're also adding the `aria-hidden` attribute on the label, since the
menu is never hidden for screen readers and so having a control to show
it could be confusing. Since the label is not focusable, we're complying
with the fourth ARIA rule:
> Do not use role="presentation" or aria-hidden="true" on a focusable
> element .
>
> Using either of these on a focusable element will result in some users
> focusing on 'nothing'.
