lander: match alternatives h3 font size with figcaption on mobile

packages/web/src/components/Lander.astro

@@ -544,6 +544,10 @@ section.alternatives {
     font-weight: normal;
     font-size: 1rem;
     flex-shrink: 0;
+
+    @media (max-width: 30rem) {
+      font-size: 0.75rem;
+    }
   }
 
   .command {