website: the two-tone headings are back, and the home page's sections are ruled apart

Two notes from the operator, 2026-10-12: the white/blue heading split was lost
in the M3 switch and should return everywhere, the apps page categories
included; and the home page's sections ran into one another.

- 41 headings get their <span> back (home 5+5, apps 6+6, FAQ 6+7, services 3+3).
  The style never went away - site.css has styled `h2 span` blue all along; the
  M3 rewrite dropped the markup. No text changed: the span wraps words that were
  already there. The three home headings that predate M3 are split where they
  were split then.
- Apps and FAQ categories are new to the treatment: a name with an & splits
  there, a phrase on its last words. Five one-word headings stay plain.
- The home page's sections get a 1px --line rule with 2.75rem of air on each
  side, so it sits centred in the gap; the first also parts the hero from the
  page. Home page only.
- Blue on the page background measures 7.9:1 - AA at any size.
- site.css ?v=28.

website/assets/site.css

@@ -2385,6 +2385,14 @@ body:not(.shell) .mobile-overlay.is-visible { opacity: 1; }
 /* --- section rhythm inside the shell's content column --- */
 .shell-section { margin-bottom: 3.5rem; }
 .shell-section:last-child { margin-bottom: 1rem; }
+/* --- the home page's sections ran into one another --------------------------
+   One long column of headings and cards with nothing but air between the
+   sections: the operator read it as one block (2026-10-12). A hairline in the
+   design system's own --line, with equal air above and below it, so the rule
+   sits centred in the gap instead of hugging the heading under it. The first
+   one also separates the hero from the page. Only the home page: every other
+   page is a single run of one kind of thing. */
+.shell.page-index .shell-section { margin-bottom: 2.75rem; padding-top: 2.75rem; border-top: 1px solid var(--line); }
 .shell .sec-head { max-width: 46rem; margin-bottom: 1.75rem; }
 .shell .sec-head h2 { font-size: clamp(1.4rem, 2.6vw, 1.9rem); font-weight: 700; letter-spacing: -.02em; margin-bottom: .4rem; }
 .shell .sec-head p { color: var(--text-2); font-size: 1rem; }