First pass for getting flow lines in place

This could use some refactoring

src/index.html

@@ -28,6 +28,12 @@
           dominant-baseline: text-after-edge;
         }
 
+        path {
+          fill: transparent;
+          stroke-width: 2px;
+          stroke: #000;
+        }
+
         circle.anchor {
           fill: #6b6659;
           stroke-width: 2px;