fix: use accent-dark with nord5 light override for prayer backgrounds

var(--color-bg-secondary) from app.css is not available since app.css
is never imported. Use var(--accent-dark) from nordtheme.css with
explicit light mode overrides using var(--nord5).

src/routes/[faithLang=faithLang]/[prayers=prayersLang]/[prayer]/+page.svelte

@@ -102,7 +102,7 @@ h1 {
 }
 .gebet-wrapper {
 	padding: 1.5em;
-	background-color: var(--color-bg-secondary);
+	background-color: var(--accent-dark);
 	box-shadow: 0 2px 4px rgba(0, 0, 0, 0.2);
 }
 .intro {
@@ -110,6 +110,11 @@ h1 {
 	font-style: italic;
 	text-align: center;
 }
+@media (prefers-color-scheme: light) {
+	.gebet-wrapper {
+		background-color: var(--nord5);
+	}
+}
 </style>
 
 <div class="container">