diff --git a/test/rendering.html b/test/rendering.html
index 9b6bedfe2..2ec58da95 100644
--- a/test/rendering.html
+++ b/test/rendering.html
@@ -4,7 +4,6 @@
     <meta charset='utf-8'>
     <title>Rendering Tests</title>
     <link rel="stylesheet" href="../css/map.css">
-    <style>body { background-color: #888; }</style>
 </head>
 <body>
     <!-- include source files here... -->
@@ -35,6 +34,20 @@
     <script src='../js/id/graph/relation.js'></script>
     <script src='../js/id/graph/way.js'></script>
 
+    <form style="position: fixed; right: 10px; bottom: 10px">
+        <input id="background-color" type="range" min="0" max="255" value="255">
+        <label for="background-color">Background Color</label>
+    </form>
+
+    <script>
+        var bg = d3.select("#background-color")
+            .on("change", function () {
+                var v = bg.property("value");
+                d3.select("body")
+                    .style("background-color", d3.rgb(v,v,v));
+            });
+    </script>
+
     <table>
         <thead>
             <tr><th></th><th colspan="3">z16</th><th colspan="3">z17</th></tr>
