<html xmlns="html">
    <head>
        <title>Hello d3 World</title>
        <!-- For stand-alone development, download Bootstrap from http://getbootstrap.com/getting-started/
             and install under your web application's root directory then modify the below link as
             appropriate. -->
        <link rel="stylesheet" href="http://netdna.bootstrapcdn.com/bootstrap/3.1.1/css/bootstrap.min.css">
    </head>
    <body>
        <div class="container">
            <div>
                <h3>Hello Rapid D3.js World</h3>
            </div>
            <!-- This is where we're going to add content with the CSS selector "#content". -->
            <div id="content"></div>
        </div>
        <!-- For stand-alone environment, download D3js from http://d3js.org/
             and install under your web application's root directory then modify the below src as
             appropriate. -->
        <script src="http://d3js.org/d3.v3.min.js"></script>
    </body>
</html>

<html xmlns="html">
    <head>
        <title>Hello d3 World</title>
        <!-- For stand-alone development, download Bootstrap from http://getbootstrap.com/getting-started/
             and install under your web application's root directory then modify the below link as
             appropriate. -->
        <link rel="stylesheet" href="https://netdna.bootstrapcdn.com/bootstrap/3.1.1/css/bootstrap.min.css">
    </head>
    <body>
        <div class="container">
            <div>
                <h3>Hello Rapid D3.js World</h3>
            </div>
            <!-- This is where we're going to add content with the CSS selector "#content". -->
            <div id="content"></div>
        </div>
        <!-- For stand-alone environment, download D3js from http://d3js.org/
             and install under your web application's root directory then modify the below src as
             appropriate. -->
        <script src="https://d3js.org/d3.v3.min.js"></script>
    </body>
</html>

Modify Bootstrap src and D3 src to HTTPS
Modify Bootstrap src and D3 src to HTTPS

depending on security settings, the browser may not load CORS links without HTTPS (my case in point, I am running my IDE from Cloud9 and it will not load these external resources without HTTPS).  It's also a modern practice to always include HTTPS when possible.