JSFiddle - React, Tailwind, and code Playground

HTML

<div id="forum-widget"></div>
<br />
<table height="500px">
    <tr>
        <td>
            <div id="left">
                <table class="forumline" width="100%" border="0" cellspacing="0" cellpadding="0" id="calendar_container">
                    <tbody>
                        <tr>
                            <td class="catLeft" height="25"><span class="genmed module-title"><strong>juli&nbsp;2013</strong></span>
                            </td>
                        </tr>
                        <tr align="center">
                            <td valign="top" class="row1">
                                <table cellpadding="3" cellspacing="1" border="0" class="forumline" style="border:0;">
                                    <tbody>
                                        <tr>
                                            <th style="padding-left:0;padding-right:0;width:14%;text-align:center;">ma</th>
                                            <th style="padding-left:0;padding-right:0;width:14%;text-align:center;">di</th>
                                            <th style="padding-left:0;padding-right:0;width:14%;text-align:center;">wo</th>
                                            <th style="padding-left:0;padding-right:0;width:14%;text-align:center;">do</th>
                                            <th style="padding-left:0;padding-right:0;width:14%;text-align:center;">vr</th>
                                            <th style="padding-left:0;padding-right:0;width:14%;text-align:center;">za</th>
                                            <th style="padding-left:0;padding-right:0;width:14%;text-align:center;">zo</th>
                                        </tr>
                                        <tr>
                                            <td class="row1" align="center" style="padding-left:0;padding-right:0;"><span class="gen">1</span>
                                            </td>
                                            <td...

CSS

div#left {
    background: #ffff00;
    width: 180px;
    height: 100%;
}

div#forum-widget.closed {
    background-position: 0px 0px;
}
div#forum-widget {
    height: 13px;
    width: 16px;
    border-radius: 4px;
    -webkit-border-radius: 4px;
    -moz-border-radius: 4px;
    cursor: pointer;
    position: absolute;
    background: #f5ebf7 url(http://i.imgur.com/zVQMs.png);
    background-position: 0px -13px;
}
.forumline { width: 180px; }

JavaScript

$("#forum-widget").on('click', function() {
    var self = this;
    $("#left").animate({
        width: 'toggle'
    }, {
        complete : function() {
            $(self).toggleClass('closed');
        }
    });
});
if($("#forum-widget").hasClass('closed')) {
    $("#left").css({
        display: 'none'
    });
}