<!doctype html>
<html>
  <head>
    <%= t.include("partials/_head.html") %>
    <link rel="stylesheet" type="text/css" href="style.css">
  </head>
  <body>

    <responsive-child>
      <!-- content goes here -->
    </responsive-child>

    <script src="app.js" async></script>
    <% if (json.project.production) { %>
    <%= !json.project.embedded ? t.include("partials/_foot.html") : "" %>
    <%= t.include("partials/_workHere.html") %>
    <% } %>
  </body>
</html>

<!doctype html>
<html lang="en-US">
  <head>
    <%= t.include("partials/_head.html") %>
    <link rel="stylesheet" type="text/css" href="style.css">
  </head>
  <body>

    <responsive-child>
      <!-- content goes here -->
    </responsive-child>

    <script src="app.js" async></script>
    <% if (json.project.production) { %>
    <%= !json.project.embedded ? t.include("partials/_foot.html") : "" %>
    <%= t.include("partials/_workHere.html") %>
    <% } %>
  </body>
</html>

Add language attribute to document
Add language attribute to document

w3c recommends including lang attribute to assist non-text readers https://www.w3.org/International/questions/qa-lang-why.en