popup.html

<!DOCTYPE html>
<html>
<head>
    <style type="text/css">
        body {
            width: 300px;
            text-align: right;
        }
        .input{
            width:270px;
        }

        .buttons{
            margin:5px;
        }
    </style>
</head>
<body>
<div class="body">
    <p>URLEncoder / Decoder</p>
    <form>
        <input type="text" id="url_to_encode" class="input"/>
        <br/>
        <input type="button" value="Current Url" id="current_url" class="buttons"/>
        <input type="button" value="encode" id="encode" class="buttons"/>
    </form>
    <br/>
    <br/>
    <form>
        <input type="text" id="url_to_decode" class="input"/>
        <br/>
        <input type="button" value="decode" id="decode" class="buttons"/>
    </form>
</div>
<script type="text/javascript" src="backend.js"></script>
</body>
</html>