.myBtn{display:block;position:fixed;bottom:20px;right:30px;z-index:99;font-size:18px;border:none;outline:none;background-color:red;color:white;cursor:pointer;padding:15px;border-radius:4px}.none{display:none}.myBtn:hover{background-color:#555}.scrollToTopButton{cursor:pointer;opacity:0;transition:opacity .3s ease-in-out}.scrollToTopButton.visible{opacity:1}