JSFiddle - React, Tailwind, and code Playground

HTML

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
     <head>
             <meta http-equiv="Content-Type" content="text/html; charset=windows-1251" />
    <title>Выпадающее меню GUI | pcvector.net</title>
    <link type="text/css" rel="stylesheet" href="css/style.css" />
	<link rel="shortcut icon" href="/favicon.ico" />
    <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.6.4/jquery.min.js"></script>
    <script src="js/custom.js"></script> 
				 <style type="text/css">
			 body {background: #ffffff url(http://pcvector.net/templates/pcv/images/bg_grid.png);}
			 </style>
</head>
<body>
    <div id="wrapper">
        <div id="container">
            <div id="settings">
                <a href="#" class="button">
                    <span class="txt">Настройки</span>
                    <span class="ar">&#9660;</span>
                </a>
                <div class="menu">
                    <ul>
                        <li><a href="#">Список</a></li>
                        <li><a href="#">Аватар</a></li>
                        <li><a href="#">Подпись</a></li>
                        <li><a href="#">Выйти</a></li>
                    </ul>
                </div>
            </div>
        </div>
    </div>
</body>
</html>

CSS

html,body,div,span,object,iframe,h1,h2,h3,h4,h5,h6,p,blockquote,pre,abbr,address,cite,code,del,dfn,em,img,ins,kbd,q,samp,small,strong,sub,sup,var,b,i,dl,dt,dd,ol,ul,li,fieldset,form,label,legend,table,caption,tbody,tfoot,thead,tr,th,td,article,aside,figure,footer,header,hgroup,menu,nav,section,menu,time,mark,audio,video{border:0;outline:0;font-size:100%;vertical-align:baseline;background:transparent;margin:0;padding:0}article,aside,figure,figcaption,footer,header,hgroup,nav,section,details,button{display:block}input[type=button],input[type=submit],button{cursor:pointer}label{cursor:text}input[type=search],input[type=text],textarea{-webkit-appearance:none}input:focus,textarea:focus{outline:none}strong,th{font-weight:700}blockquote,q{quotes:none}button{border:0}a{font-size:100%;vertical-align:baseline;text-decoration:none;background:transparent;margin:0;padding:0}ins{background-color:#fff;color:#000;text-decoration:none}mark{background-color:#fff;color:#000;font-style:italic;font-weight:700}del{text-decoration:line-through}abbr[title],dfn[title]{border-bottom:1px dotted #000;cursor:help}html{overflow-y:scroll;-webkit-font-smoothing:antialiased}hr{background:#d9d9d9;color:#d9d9d9;line-height:0;width:100%;height:1px;border:none;display:block;margin:0 0 60px;padding:0}nav ul,ul{list-style:none}::-moz-selection,::selection{background:#ff4800;color:#fff}

/*----------------
BODY
----------------*/
html, body {
width: 100%;
height:100%;
color:#484e57; 
font: normal 12px/22px Arial, sans-serif;
text-align:left;
background:#fff;
margin:0;
text-shadow:0 0 1px transparent;
}

a, a:visited { color:#879199; text-decoration:none }

#wrapper { width:100%; height:100%; position:relative }
#container { width:960px; margin:0 auto }

#settings { width:192px; position:absolute; top:50%; left:50%; margin:-30px 0 0 -96px; }

/*---------------------------
Button Default
---------------------------*/

.button { 
    padding:8px 10px;
    border:1px solid #caced9;
   ...

JavaScript

$(function() {

    var button = $('.button');
    var menu = $('.menu');
    
    $('ul li a', menu).each(function() {
        $(this).append('<span />');
    });
    
    button.toggle(function(e) {
        e.preventDefault();
        menu.css({display: 'block'});
        $('.ar', this).html('&#9650;').css({top: '3px'});
        $(this).addClass('active');
    },function() {
        menu.css({display: 'none'});
        $('.ar', this).html('&#9660;').css({top: '5px'});
        $(this).removeClass('active');
    });
    
    button.click()
        
});