form表单 datalist 和legend

<form action="" method="post" >
    <fieldset>
        <legend>
            表单元素
        </legend>


        <input type="text" placeholder="请输入">

        <input type="text" list="mylist" placeholder="输入或选择">
        <datalist id="mylist">
            <option value="1">1</option>
            <option value="2">2</option>
            <option value="3">3</option>
        </datalist>

    </fieldset>

</form>