* Don't hide page content when displaying search
* Decrease sidebar animation time
* Fix search key event handler
which wasn't completely de-jqueryified.
* Avoid reflowing page content on small screens
This reduces jank caused by reflowing the page text while animating the
sidebar, and it looks nicer.
* Don't use HTMLParentNode.prepend()
since edge doesn't support it yet
* Don't animate menu border bottom color
since it's the same color as the background, which isn't animated.
* Small CSS improvments
- Remove invalid `pointer: cursor` style
- Disable transitions for noscript to stop page from spazzing on every load
- Add `cursor: pointer` to mark
- Disable `cursor: pointer` on noscript menu-title
* JS fixes
- Load MathJax async
- Always use local fontawesome and clipboard.js
- Move js class to html element to make theme switching easier
* Give the print button a bit more margin
* This is a built-in function of iOS Safari that didn't work because the
page content was inside absolutely-positioned, scrollable divs.
* The fix is to stop using absolute positioning on `.page-wrapper` and
`.page`, so that the content uses static positioning and flows
naturally down the page.
* Consequently, `.sidebar` and `.nav-chapter` now have to use `position:
fixed` in order to be positioned relative to the viewport.
* This fix also enables Safari's built-in behavior of automatically
hiding the top and bottom toolbars when scrolling down the page.
