diff --git a/app.js b/app.js
index 441baab..0b06912 100644
--- a/app.js
+++ b/app.js
@@ -24,10 +24,10 @@ var linksData = [
 ];
 
 var nodes = d3.select("#nodes")
-        .selectAll("circle")
-        .data(nodesData)
-        .enter()
-        .append("circle");
+    .selectAll("circle")
+    .data(nodesData)
+    .enter()
+    .append("circle");
 
 d3.forceSimulation()
     .nodes(nodesData)
diff --git a/index.html b/index.html
index 3032a97..b2261d8 100644
--- a/index.html
+++ b/index.html
@@ -9,6 +9,7 @@
     <body>
         <svg>
             <g id="nodes"></g>
+            <g id="links"></g>
         </svg>
         <script src="app.js" charset="utf-8"></script>
     </body>
