JSFiddle - React, Tailwind, and code Playground

HTML

<div id="content">
    <ul>
        <li><a id="a1" href="#"></a>
        </li>
        <li><a id="a2" href="#"></a>
        </li>
        <li><a id="a3" href="#"></a>
        </li>
    </ul>
</div>
<!-- #content -->
<div id="header">	<a id="logotipo" href=""></a>

    <ul>
        <li><a href="#">menu1</a>
        </li>
        <li><a href="#">menu2</a>
        </li>
        <li><a href="#">menu3</a>
        </li>
        <li><a href="#">menu4</a>
        </li>
    </ul>
</div>
<!-- #header -->
<div class="clear"></div>
<!-- CLEAR! -->
<div id="footer"><span>Footer</span>
</div>
<!-- #footer -->

CSS

/* Solução */
 #content, #footer {
    position:relative;
}
#content {
    z-index:2;
}
#footer {
    z-index:3;
}
/* Fim solução */

/*--------------RESEST------------------------------*/
 html, body, div, span, applet, object, iframe, input, h1, h2, h3, h4, h5, h6, p, blockquote, pre, a, abbr, acronym, address, big, cite, code, del, dfn, em, img, ins, kbd, q, s, samp, small, strike, strong, sub, sup, tt, var, b, u, i, center, dl, dt, dd, ol, ul, li, fieldset, form, label, legend, table, caption, tbody, tfoot, thead, tr, th, td, article, aside, canvas, details, embed, figure, figcaption, footer, header, hgroup, menu, nav, output, ruby, section, summary, time, mark, audio, video {
    margin: 0;
    padding: 0;
    border: 0;
    font-size: 100%;
    font: inherit;
    vertical-align: baseline;
}
/* HTML5 display-role reset for older browsers */
 article, aside, details, figcaption, figure, footer, header, hgroup, menu, nav, section {
    display: block;
}
body {
    line-height: 1;
}
ol, ul {
    list-style: none;
}
blockquote, q {
    quotes: none;
}
blockquote:before, blockquote:after, q:before, q:after {
    content:'';
    content: none;
}
table {
    border-collapse: collapse;
    border-spacing: 0;
}
/*-------FIM DO RESET-----------------------------------------------------*/
 .clear {
    clear:both;
}
body {
    background-color:#cfcfcf;
    font-family:Verdana, Arial, Helvetica, sans-serif;
    overflow:hidden;
}
#header {
    position:relative;
    left:546px;
    width:380px;
    height:487px;
    padding-top:15px;
    padding-left:125px;
    background-size:cover;
}
#logotipo {
    display:block;
    margin-left:18px;
    background:#993366;
    width:340px;
    height:66px;
}
#header ul {
    position:absolute;
    margin-left:20px;
}
#header li {
    margin:20px 0;
}
#header li:nth-child(1) {
    margin-left:2px;
}
#header li:nth-child(2) {
    margin-left:50px;
}
#header li:nth-child(3) {
    margin-left:100px;
}
#header li:nth-child(4) {
   ...