Landing: link the overlays page

index.html

@@ -44,6 +44,11 @@ a.card p{margin:0;color:var(--muted);font-size:12.5px}
       <p>Spin the yantra and its inversion on the Riemann sphere, with the plane underneath. Slide the lift, compare stereographic with great circles, and switch the sphere off to see just the plane.</p>
       <span class="go">open explorer →</span>
     </a>
+    <a class="card" href="overlay/">
+      <h2>Overlays</h2>
+      <p>The yantra laid over its own inversions: one in the outer rim, one in a smaller circle tuned so the trefoil's lobe meetings land on the outer triangle's midpoints. Toggle any of the three.</p>
+      <span class="go">open overlays →</span>
+    </a>
   </div>
   <section class="notes">
     <p><span class="dot" style="background:var(--up)"></span>four upward triangles · <span class="dot" style="background:var(--down)"></span>five downward · <span class="dot" style="background:var(--bindu)"></span>the bindu</p>