Untitled

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<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Lists</title>
</head>
<body>
    <ol type="I">
        <li>List item 1
            <ol type="a">
                <li>Nested item 1.1</li>
                <li>Nested item 1.2</li>
            </ol>
        </li>

        <li>List item 2
            <ol type="1">
                <li>Nested item 2.1</li>
                <li>Nested item 2.2
                    <ul type="circle">
                        <li>Nested item 2.2.1</li>
                        <li>Nested item 2.2.2</li>
                        <li>Nested item 2.2.3</li>
                    </ul>
                </li>
                <li>Nested item 2.3</li>
            </ol>
        </li>

        <li>List item 3
            <ul type="disc">
                <li>Nested item 3.1</li>
                <li>Nested item 3.2</li>
                <li>Nested item 3.3</li>
            </ul>
        </li>
    </ol>
</body>
</html>