<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8">
    <meta http-equiv="X-UA-Compatible" content="IE-edge">
    <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
    <title>Helium</title>
    <base href="/">
    <link href="https://fonts.googleapis.com/css?family=Roboto" rel="stylesheet">
    <link href="https://fonts.googleapis.com/icon?family=Material+Icons"
      rel="stylesheet">
    <link rel="shortcut icon" href="/metadata/favicon.ico" type="image/x-icon">
    <link rel="manifest" href="/metadata/manifest.json">
</head>
<body>
    <app></app>
</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="utf-8">
    <meta http-equiv="X-UA-Compatible" content="IE-edge">
    <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
    <title>Helium</title>
    <base href="/">
    <link href="https://fonts.googleapis.com/css?family=Roboto" rel="stylesheet">
    <link href="https://fonts.googleapis.com/icon?family=Material+Icons"
      rel="stylesheet">
    <link rel="shortcut icon" href="/metadata/favicon.ico" type="image/x-icon">
    <link rel="manifest" href="/metadata/manifest.json">
</head>
<body>
    <app></app>
</body>
</html>

Add lang attribute to <html> tag
Add lang attribute to <html> tag
