JSFiddle - React, Tailwind, and code Playground

HTML

<div id="ScrollToTopHolder"><a href="#Top" id="ScrollToTop">Top</a></div>

CSS

body {
    height: 2000px;
    background: #990000;
}
#ScrollToTopHolder {
    position: fixed;
    width:100%;
    bottom:0px;
}
#ScrollToTop {
    position: absolute;
    right: 0px;
    bottom: -10px;
    width: 50px;
    height: 50px;
    line-height: 50px;
    background: #fff;
    color: #000;
    text-transform: uppercase;
    text-decoration: none;
    text-align: center;
    font-size: 15px;
    font-weight: bold;
    z-index: 1000;
    border: solid 1px #000;
    border-bottom: none;
    border-radius: 10px 10px 0 0;
    transition: all 0.4s;
}
#ScrollToTop:hover {
    bottom: 0px;
}