Init with zooming and brushing

css/main.css

@@ -92,6 +92,17 @@ body {
   padding-left: 1.25rem;
 }
 
+.area {
+  fill: steelblue;
+  clip-path: url(#clip);
+}
+
+.zoom {
+  cursor: move;
+  fill: none;
+  pointer-events: all;
+}
+
 #toggle-btn{
   text-align: center;
 }