JSFiddle - React, Tailwind, and code Playground

HTML

<div id="main">
    <div id="header"></div>
    <div id="contents-box">
        <div id="contents">
            <p>Some text</p>
            <p>etc</p>
            <p>etc</p>
            <p>etc</p>
            <p>etc</p>
            <p>etc</p>
        </div>
    </div>
    <div id="footer"></div>
</div>

CSS

#main {
}
#header {
    position: relative;
    height:100px;
    background:#151515;
    z-index: -1;
}
#contents-box {
    border: dashed grey 1px; /* for understanding only, remove it in the end */
    z-index: 1;
    margin-top: -30px;
    margin-bottom: -30px;
    /* TODO: address min-height; try only one line of text. */
    /* fixed height would work too, but would not let the box stretch dynamically */
}
#contents {
    width: 75%;
    height: 100%;
    margin: 0 auto;
    background: grey;
    z-index: 1;
}
#footer {
    position: relative;
    height:75px;
    background:#151515;
    z-index: -1;
}