Follow the OS dark mode with a softer, readable palette

Elternbeirat.Web/Components/Layout/MainLayout.razor.css

@@ -26,8 +26,9 @@
    through as it scrolls underneath. */
 .site-header {
     /* Brand-blue bar with a warm accent underline -- the strongest, most visible
-       cue that carries the friendly tone across every page. */
-    background: var(--color-brand);
+       cue that carries the friendly tone across every page. Uses its own header
+       token so it stays deep blue in dark mode too (see app.css). */
+    background: var(--color-header);
     border-bottom: 3px solid var(--color-accent);
     box-shadow: var(--shadow);
     position: sticky;