fix: Defer initial WebGL render until DOM layout completes for auto-loaded STL

web/model-viewer.js

@@ -349,6 +349,11 @@
     frame = 0;
     if (!vertexCount) return;
     const rect = canvas.getBoundingClientRect();
+    if (rect.width < 10 || rect.height < 10) {
+      // Container layout is not ready yet; retry on next frame
+      requestDraw();
+      return;
+    }
     const width = Math.max(1, Math.round(rect.width * renderScale));
     const height = Math.max(1, Math.round(rect.height * renderScale));
     if (canvas.width !== width || canvas.height !== height) {
@@ -503,6 +508,9 @@
       yawVelocity = 0;
       pitchVelocity = 0;
 
+      // Defer rendering to post-reflow rAF so canvas dimensions are ready
+      requestAnimationFrame(() => {
+        requestDraw();
         setTimeout(() => {
           introAnimating = true;
           introStartTime = performance.now();
@@ -511,6 +519,7 @@
           startZoom = zoom;
           requestDraw();
         }, 150);
+      });
 
       requestDraw();
       return { name, triangles: vertexCount / 3 };