feedback1 final: the loadout screen's background layer draws again (pointed out in PR #14)

css/screens/loadout.css: `.lo > * { position: relative }` (one class, a later rule) overrode `.lo__bg { position:
absolute }`, so the mint glow / grid layer was a 0-px flex item and never rendered. `.lo > :where(:not(.lo__bg))`
keeps the one-class specificity for every other layer and never matches the background.

Checked in headless Chrome at 1920x1080 and 844x390 (touch): the layer now covers the overlay (0 px tall before),
every other box of the screen is unchanged, no console errors. Tests: test/ui/loadout.test.js (the cascade; fails on
the old rule), opt-in test/ui/loadout.e2e.test.js (the layer's box and stacking at both sizes). DESIGN §21.25 credits
PR #14 and PR #10 (crossOrigin on the two new Image() loads); CHANGELOG 0.1.1 lines for both.

public/css/screens/loadout.css

@@ -26,7 +26,10 @@
     linear-gradient(90deg, rgba(78, 216, 175, .035) 1px, transparent 1px) 0 0 / .6rem .6rem,
     linear-gradient(180deg, #0f1312, #090b0a);
 }
-.lo > * { position: relative; }
+/* every layer but the background stacks above it. :where() keeps this at the specificity of the old `.lo > *` (one
+   class), so the rules after it still win where they did, and it never matches .lo__bg: as `.lo > *` (same specificity,
+   later rule) it beat the layer's `position: absolute`, which left a 0-px tall flex item that never drew (PR #14). */
+.lo > :where(:not(.lo__bg)) { position: relative; }
 
 /* ---- top bar ---------------------------------------------------------------------------------------------------- */
 .lo-top {