{# every swap on the page morphs by default: what is on screen is diffed into what came back, so scroll, hover and focus survive a change of page #} {# every request says which build the page is; a page left open across an upgrade is told so and covered until its reader refreshes it, rather than patched with pieces of the new one - and from then on asks for nothing, whatever on it would have #}
{% include "rail.html" %}
{% include content %}
{# when the server cannot be reached at all, nothing can come from it; the board for that case is carried in the page from the start #}