関連ワード:  header content type text html    header (' content type text html charset utf 8 ')    php header content type text html    response header content type text html charset utf 8    incorrect http header content type text html expected application xml    self send_header (' content type text html ')    ignoring header field content type text html    mailx ignoring header field content type text html    content type header is text html not application json    add_header content type text html