JSFiddle - React, Tailwind, and code Playground

HTML

<article class="brackets">
    <div class="bracketsbg"></div>
    <section id="group">
         <h2><a href="#group">Group Stage</a></h2>

        <div class="groups">
            <ul>
                <li>A</li>
                <li>B</li>
                <li>C</li>
                <li>D</li>
            </ul>
        </div>
    </section>
    <section id="knockout">
         <h2><a href="#knockout">Knockout Stage</a></h2>

        <div class="groups">
            <ul>
                <li>E</li>
                <li>F</li>
                <li>G</li>
                <li>H</li>
            </ul>
        </div>
    </section>
</article>

CSS

article.brackets {
    background: black;
    position: relative;
    display: block;
    width: 914px;
    height: 300px;
    margin: 40px auto;
}
.bracketsbg {
    position: absolute;
    background-color: black;
    width: 914px;
    opacity: 0.6;
    height: 100%;
    z-index: 1;
}
article.brackets section {
    position: absolute;
    display: block;
    top: 0em;
    left: 0;
    height: 700px;
    width: 914px;
    padding: 5px 0px;
    border-radius: 5px;
    box-shadow: 0 3px 3px rgba(0, 0, 0, 0.1);
    z-index: 2;
}
article.brackets section:first-child {
    z-index: 0;
}
article.brackets section h2 {
    position: absolute;
    font-size: 1em;
    font-weight: normal;
    width: 135px;
    height: 1.8em;
    top: -1.8em;
    left: 10px;
    padding: 0px;
    margin: 0;
    color: red;
    /*other tab color*/
    background-color: white;
    /*other tab background*/
    border-radius: 5px 5px 0 0;
}
article.brackets section:nth-child(2) h2 {
    left: 10px;
}
article.brackets section:nth-child(3) h2 {
    left: 150px;
}
article.brackets section h2 a {
    display: block;
    width: 100%;
    line-height: 1.8em;
    text-align: center;
    text-decoration: none;
    color: black;
}
article.brackets section p {
    text-align: center;
}
article.brackets section:target, article.brackets section:target h2 {
    color: black;
    /*current tab text color*/
    z-index: 2;
}
.groups {
    text-align: center;
    margin: 30px 300px;
    background: #0000CC;
}
.groups li {
    display: inline;
    padding-left: 0px;
    padding-right: 50px;
    color: white;
    border: 2px;
    border-color: black;
    font-weight: bold;
}