JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container">
    <a class="button7" href="http://google.co.uk" onmouseover="displayFavorite('000')" onmouseout="hideFavorite('000')">
    Math 141
    
    <ul>
        <li><strong>Description</strong> Calculus 1 and Calulus 2</li>
        <li><strong>Instructor</strong> Boon Ong</li>
        <li><strong>Documents</strong> 17</li>
    </ul>
</a>
<button id='000' class="button8" onclick="favorite('000')">Favorite</button>
</div>

CSS

.container {
    position:relative;
    width:400px;
}
.button7 {
    width:100%;
    height:auto;
    display:block;
    background:red;
}
.button8 {
    position:absolute;
    top:5px;
    right:5px;
}