Remove custom font size and line spacing

* Use larger bootstrap defaults
Show a more useful TNA timestamp

* Make the date human readable
* Return a copyable version that can be pasted into a National archive
URL
Create muted-link class

* Refactor the redirect-to-link class for wider use
* Add to the style guide
Refactor out redirects-to class

* We can use bootstrap’s mute instead
Refactor js class toggle

* Avoid repaints by toggling JS class before CSS has loaded
* Use a class for enabled and disabled
* Use minified inline JavaScript instead
* This also mimics the Modernizr approach
Cleanup base CSS

* Separate into sections with comments
* Include content toggle classes
* Remove body and pre styles that aren’t being used, or are met by
bootstrap defaults
Move archive & suggested URLs behind disclosures

* Archive and suggested URLs are secondary fields that rarely need to
be filled in, move them behind a disclosure to avoid confusion
* Introduce text that explains the meaning of both URL types, with
appropriate link text to disclose the fields
* Use cancel or remove to switch the view back and reset the field
* Default to showing the fields when they are present
* Switch labels for read only fields to a key-value definition list
that simulates label styles
* Introduce a mappings helper to create national archive URLs
* When JS is disabled, show all form values and separate the form with
visible legends, and hide JS interactions
* Behaviour when creating mapping still TBD
* There is known caveat that if the default host is wrong the national
archive link may not work and that the fix isn’t clear to the user
Change TNA messaging when creating a mapping

* We can’t show a national archive link until the mapping path is
canonicalised
* Hide the TNA link and alternative field