Edit in JSFiddle

<html>
    <head>
        <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
        <script type="text/javascript" src='JavaScriptSpellCheck/include.js'></script>
        <script type="text/javascript">
            function checkspell()
            {
                $Spelling.SpellCheckInWindow('textarea');
            }
        </script>
        <style>
            body
            {
                margin:0 auto;
                padding:0px;
                text-align:center;
                width:100%;
                font-family: "Myriad Pro","Helvetica Neue",Helvetica,Arial,Sans-Serif;
                background-color:#CEE3F6;
            }
            #wrapper
            {
                margin:0 auto;
                padding:0px;
                text-align:center;
                width:995px;
            }
            #text_div
            {
                margin-top:20px;
            }
            #text_div textarea
            { 
                width:500px;
                height:150px; 
                border:none;
                padding:10px;
                font-size:17px;
            }
            #text_div input[type="button"]
            {
                background-color:#0080FF;
                border:none;
                color:white;
                width:200px;
                height:40px;
                border-bottom:4px solid #0174DF;
                border-radius:3px;
            }
        </style>
    </head>
    <body>
        <div id="wrapper">
            <div id="text_div">
                <textarea id="textarea" placeholder="Enter Some Text"></textarea>
                <br>
                <input type="button" onclick="checkspell();" value="CHECK SPELLING">
            </div>
        </div>
    </body>
</html>