Take the cone down and turn it blue

Lower alpha through the whole fill (0.34 -> 0.19 at the strings, falling with
depth) and the core is a LIT BLUE rather than near-white, which is what was
washing it out. The stroked edges come down and turn blue with it.

Worth recording, because it will come up again: the cone's opacity and how well
you can tell above-the-plane from below-the-plane are the same dial. The plane is
flat -- a body above it is drawn clean on top, a body below is seen through it --
so the distinction just IS the cone's alpha. Fainter cone and sharper split pull
against each other; the fainter cone wins and the cut line carries the signal.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

index.html

@@ -179,6 +179,6 @@
     </div>
   </div>
 </div>
-<script type="module" src="main.js?v=105"></script>
+<script type="module" src="main.js?v=106"></script>
 </body>
 </html>