&lt!DOCTYPE html>
    &lthtml lang="en">
    &lthead>
        &lttitle>{% block title %}My Site{% endblock %}
        {% block css %}
        {% endblock %}
        &ltmeta name="viewport" content="width=device-width, initial-scale=1.0">
      &lt/head>
    &ltbody>
    Hello, world!
    &lt/body>
    &lt/html>