<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"  "http://www.w3.org/TR/html4/strict.dtd">
<html lang="en">
<head>
<meta http-equiv="content-type" content="text/html; charset=utf-8">
<link href="css/newtab.css" rel="stylesheet" type="text/css">
</head>

<body>
    <div id="top_menu_container">
        <ul id="top_menu">
            <li><a id="top_menu_settings" class="white_text" href="" data-l10n-id="settings"></a></li>
        </ul>
    </div>

    <div id="clock_container">
        <span id="time" class="white_text"></span>
        <span id="time_ampm" class="white_text"></span>
    </div>
</body>

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<link href="css/newtab.css" rel="stylesheet" type="text/css">
</head>

<body>
    <div id="top_menu_container">
        <ul id="top_menu">
            <li><a id="top_menu_settings" class="white_text" href="" data-l10n-id="settings"></a></li>
        </ul>
    </div>

    <div id="clock_container">
        <span id="time" class="white_text"></span>
        <span id="time_ampm" class="white_text"></span>
    </div>
</body>

Update from html4 to html5 tags
Update from html4 to html5 tags
