JSFiddle - React, Tailwind, and code Playground

HTML

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1">
   <meta name="viewport" content="width=device-width, initial-scale=1.0" />
  <title>Editor</title>
</head>
<body>


<form action="#" method="post">


<pre id="editor">

    #editor { 
        margin: 0;
        position: absolute;
        top: 0;
        bottom: 0;
        left: 0;
        right: 0; font-size: 18px !important;
        overflow: hidden;
    }
    .ace_print-margin {
      display: none !important; 
    } 

    #editor_body {
      position: absolute;top: 0;
        bottom: 0;
        left: 0;
        right: 0;
    }

     .submit_but {
      position: absolute; bottom: 10px; right: 20px;
      background: #fff; border: none; padding: 5px 20px;
    margin-top: 20px; border-radius: 5px;-webkit-border-radius: 5px;-moz-border-radius: 5px; font-size: 16px;font-weight: bold; font-family: Tahoma; cursor: pointer;
     }

    .submit_but {
      position: absolute; bottom: 10px; right: 20px;
      background: #fff; border: none; padding: 5px 20px;
    margin-top: 20px; border-radius: 5px;-webkit-border-radius: 5px;-moz-border-radius: 5px; font-size: 16px;font-weight: bold; font-family: Tahoma; cursor: pointer;
     }

     .submit_but {
      position: absolute; bottom: 10px; right: 20px;
      background: #fff; border: none; padding: 5px 20px;
    margin-top: 20px; border-radius: 5px;-webkit-border-radius: 5px;-moz-border-radius: 5px; font-size: 16px;font-weight: bold; font-family: Tahoma; cursor: pointer;
     }



</pre>

<div></div>

<input type="submit" value="Save" class="submit_but">

</form>
 <script src="http://d1n0x3qji82z53.cloudfront.net/src-min-noconflict/ace.js" type="text/javascript" charset="utf-8"></script>
</body>
</html>

CSS

body {
         overflow: auto; height: 100%; width: 100%; clear: both;
    }
    
    #editor { 
        margin: 0;
        position: fixed;
        top: 0;
        bottom: 0;
        left: 0;
        right: 0; font-size: 18px !important;
        overflow: auto; height: 100%;
    }
    .ace_print-margin {
      display: none !important; 
    } 



     .submit_but {
      position: absolute; bottom: 10px; right: 20px;
      background: #fff; border: none; padding: 5px 20px;
    margin-top: 20px; border-radius: 5px;-webkit-border-radius: 5px;-moz-border-radius: 5px; font-size: 16px;font-weight: bold; font-family: Tahoma; cursor: pointer;
     }

JavaScript

var editor = ace.edit("editor");
    editor.setTheme("ace/theme/twilight");
    editor.getSession().setMode("ace/mode/css");