JSFiddle - React, Tailwind, and code Playground

HTML

<html>

  <head>
    <meta charset="utf-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width,initial-scale=1.0">
    <title> Simple Back To Top Floating Button </title>
  </head>

  <body style="background-color: rgba(84,160,245,0.51)">
    <div style="padding:15px 15px 2500px;font-size:30px">
      <p><b>Scroll down and click the button</b></p>
      <p>Scroll down this frame to see the effect!</p>
      <p>Scroll Baby SCROLL!!</p>
      <p>Lorem ipsum dolor dummy text sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis
        aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.</p>
    </div>


    <button id="topButton" onclick="scrollToTop()"><img...

CSS

#topButton {
  position: fixed;
  bottom: 25px;
  float: right;
  right: 10%;
  left: 90%;
  max-width: 50px;
  width: 100%;
  font-size: 14px;
  border-color: rgba(85, 85, 85, 0.2);
  background-color: #99cbcf;
  padding: 1px;
  border-radius: 4px;
  cursor: pointer;
  color: #000
}

#topButton:hover {
  background-color: #7dbbf1;
}