Adding some styling to start and end anchors

src/index.html

@@ -34,12 +34,20 @@
           stroke: #000;
         }
 
-        circle.anchor {
+        circle.pin {
           fill: #6b6659;
           stroke-width: 2px;
           stroke: #000;
         }
 
+        .anchor text {
+          fill: #fff;
+        }
+
+        .anchor rect {
+          fill: #6b6659;
+        }
+
         .placeholder text {
           fill: #fff;
           font-weight: bold;