demo.css

body {
  padding: 50px;
  margin: 0 auto;
  background-color: black;
  color: white;
  background-image: url(img/black-pattern.png);
}

.win-coffee, .win-tea, .win-espresso, .lose {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: 20;
  background-size: 100% 100%;
  background-repeat: no-repeat;
}

.win-coffee {
  background-image: url(img/win-coffee.jpg);
}

.win-tea {
  background-image: url(img/win-tea.jpg);
}

.win-espresso {
  background-image: url(img/win-espresso.jpg);
}

.slot-machine .lose {
  background-image: url(img/lose.jpg);
}

h1 { text-align: center;  }
.slot-machine { margin: 0 auto; }
#forkongithub a{background:#000;color:#fff;text-decoration:none;font-family:arial,sans-serif;text-align:center;font-weight:bold;padding:5px 40px;font-size:1rem;line-height:2rem;position:relative;transition:0.5s;}#forkongithub a:hover{background:#c11;color:#fff;}#forkongithub a::before,#forkongithub a::after{content:"";width:100%;display:block;position:absolute;top:1px;left:0;height:1px;background:#fff;}#forkongithub a::after{bottom:1px;top:auto;}@media screen and (min-width:800px){#forkongithub{position:fixed;display:block;top:0;right:0;width:200px;overflow:hidden;height:200px;z-index:9999;}#forkongithub a{width:200px;position:absolute;top:60px;right:-60px;transform:rotate(45deg);-webkit-transform:rotate(45deg);-ms-transform:rotate(45deg);-moz-transform:rotate(45deg);-o-transform:rotate(45deg);box-shadow:4px 4px 10px rgba(0,0,0,0.8);}}