fix(rcart): resolve merge conflict — combine centering + subnav hiding

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

modules/rcart/components/cart.css

@@ -6,9 +6,14 @@ main {
 
 /*
  * Narrow page components (payment page, request form, dashboard, group buy)
- * already set their own max-width + margin:0 auto for centering.
- * We just need to ensure the subnav still spans full width above them.
+ * set their own max-width; we center them with margin auto so subnav stays full-width.
  */
+folk-payment-request,
+folk-payment-page,
+folk-group-buy-page,
+folk-payments-dashboard {
+	margin: 0 auto;
+}
 
 /* Hide the module subnav on public-facing pages — payers/pledgers don't need shop nav */
 main:has(folk-payment-page) .rapp-subnav,