I built an HTML page to display it as an iframe and on desktop everything works fine. Now I would like to make it responsive and transform the layout of the content via media queries. I don't know what is going on but the HTML element keeps a width of 960px. I used Atom and it gave me a HTML structure that I used for a simple test.
<!DOCTYPE html>
<html lang="de" dir="ltr">
    <head>
        <meta charset="utf-8">
        <title>Viewport Test</title>
        <style media="screen">
            body {
                text-align: center;
            }
        </style>
    </head>
    <body>
        <span>TEST</span>
    </body>
</html>
I use the dev tools of Chrome to test the responsive layout and I set the width of the window to 360px but the HTML document keeps at 960px. I cant understand what's going on here. Please help me and thank you.