Show the backward equation under reduced motion

The reduced-motion rule for Figura II reads `:not(:first-of-type)`, and
`:first-of-type` counts element types rather than classes. All six equations
are spans, so only the very first span was ever "first of type" — which kept
forward equation one and silently hid every backward one. The comment beside
it promises that "one from each phase stands"; only the forward phase did.

The sibling combinator says what was meant: hide a forward equation that
follows a forward equation, and likewise for backward. Reduced-motion readers
now get "the unit" and "the loss" together, which is the pair that makes the
figure legible without the cycle to explain it.

Found from a screenshot of the page on a handset with Reduce Motion on. The
single equation in that image is also what proves the setting is on rather
than the animation being frozen: `np-eq-f` opens at `opacity: 0` with no fill
mode, so a stalled clock renders the slot empty, and only the reduced-motion
rule makes it visible while still.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Author: asifuddin01

src/components/elementa/NetworkPlate.astro

@@ -286,7 +286,12 @@ const BACKWARD = EDGES.filter((e) => e.rg > 0.3);
        sitting empty under a network with no explanation. */
     .np-eq { min-height: 5rem; align-content: center; gap: 0.35rem; }
     .np-eq-i { position: static; opacity: 1; }
-    .np-eq-f:not(:first-of-type), .np-eq-b:not(:first-of-type) { display: none; }
+    /* `:first-of-type` counts element types, and all six equations are
+       spans — so only the very first span was ever "first of type", which
+       kept forward equation 1 and silently hid every backward one. The
+       sibling combinator says what was meant: hide any forward equation
+       that follows a forward equation, and likewise for backward. */
+    .np-eq-f ~ .np-eq-f, .np-eq-b ~ .np-eq-b { display: none; }
   }
 
   @media all {