JSFiddle - React, Tailwind, and code Playground

HTML

<div class="grey-box-wrap">
    <div class="top">
        <a href="javascript:;" class="prev"><i></i>previous week</a>
        <span class="center">February 04 - February 10, 2013 (week 6)</span>
        <a href="javascript:;" class="next">next week<i></i></a>
    </div>
    <div class="bottom">
        <ul class="days">
            <li>
                <a href="javascript:;">
                    <b>Feb 04</b>
                    <!-- <i>7.5</i> -->
                    <span>monday</span>
                </a>
            </li>
            <li>
                <a href="javascript:;">
                    <b>Feb 06</b>
                    <!-- <i>7.5</i> -->
                    <span>tuesday</span>
                </a>
            </li>
            <li>
                <a href="javascript:;">
                    <b>Feb 06</b>
                    <!-- <i>7.5</i> -->
                    <span>wednesday</span>
                </a>
            </li>
            <li class="active">
                <a href="javascript:;">
                    <b>Feb 07</b>
                    <!-- <i>7.5</i> -->
                    <span>thursday</span>
                </a>
            </li>
            <li>
                <a href="javascript:;">
                    <b>Feb 08</b>
                    <!-- <i>7.5</i> -->
                    <span>friday</span>
                </a>
            </li>
            <li>
                <a href="javascript:;">
                    <b>Feb 09</b>
                    <!-- <i>0.0</i> -->
                    <span>saturday</span>
                </a>
            </li>
            <li class="last">
                <a href="javascript:;">
                    <b>Feb 10</b>
                    <!-- <i>0.0</i> -->
                    <span>sunday</span>
                </a>
            </li>
        </ul>
    </div>
</div>
<div class="row-wrapper">

CSS

.active {
    color: red;
}

.active a {
    color: red;
}

JavaScript

$(document).ready(function() {
    $('li a').click(function() {
        $('li').each(function() {
            $(this).removeClass('active');    
        });
        
        $(this).parent().addClass('active');
    });
});