add_action('wp_enqueue_scripts', function() {
    // get protocol used by current page
    $protocol = is_ssl() ? 'https' : 'http';

    // build list of font families to add
    $font_families = array();
    $font_families[] = 'The+Girl+Next+Door:400';    // only has normal/400

    // build arguments list for Google Fonts
    $fonts = array(
        'family' => implode('|', $font_families),
        'subset' => 'latin,latin-ext',
    );

    // enqueue the stylesheet
    wp_enqueue_style('website-fonts', add_query_arg($fonts, "$protocol://fonts.googleapis.com/css" ), array(), null);
});