Add NAURUA foundation overrides

foundations.html

@@ -88,6 +88,22 @@
     </table>
   </section>
 
+  <section id="foundations-portal-overrides">
+    <h2 class="sg-sub-heading sg-text-on-dark">Portal Overrides</h2>
+    <table class="sg-foundation-table sg-table-label">
+      <thead>
+        <tr>
+          <th>Portal</th>
+          <th>Abweichung</th>
+          <th>Verwendung</th>
+        </tr>
+      </thead>
+      <tbody>
+        <tr><td>NAURUA</td><td>darkblue → #354A52; body → Avenir, sans-serif</td><td>Portalgebundene Foundation-Overrides für das zweite Portal. Die Überschreibung greift nur, wenn das Root-Element `data-portal="naurua"` setzt.</td></tr>
+      </tbody>
+    </table>
+  </section>
+
   <section id="foundations-spacing">
     <h2 class="sg-sub-heading sg-text-on-dark">Spacing</h2>
     <table class="sg-foundation-table sg-table-label">

styles/01-foundations.css

@@ -305,3 +305,8 @@
   --sg-slider-progress: 0%;
   --chart-label-position: var(--chart-label-position-default);
 }
+
+:root[data-portal="naurua"] {
+  --color-darkblue: #354A52;
+  --font-family-base: "Avenir", sans-serif;
+}