body{ margin: 0; overflow: hidden; width: 100%; } #guide{ width:80%; border: solid black 3px; background:rgb(255, 255, 255, 0.5); display: none; position: fixed; z-index: 1000; bottom: 20%; left: 50%; transform: translate(-50%, -20%); } #btn{ color: white; text-align: center; position: fixed; display:block; left: 45%; bottom: 5%; transform: translate(-5%, -50%); background: rgb(0, 0, 0, 0.2); border: solid white 2px; border-radius: 50%; width: 50px; height: 50px; font-size: large; } #btn:hover{ color: black; background: rgb(255, 255, 255, 0.8); border: black; transition: .4s; }