devtool/src/panel.html
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0">
<meta name="description" content="Cycle.js DevTool"/>
<link href="//fonts.googleapis.com/css?family=Source+Sans+Pro:200,300,400,600,700,200italic,300italic,400italic,600italic,700italic" rel="stylesheet" type="text/css">
<title>Cycle.js DevTool</title>
</head>
<body>
<div id="tools-container"></div>
<script src="./panel.js"></script>
</body>
</html>