* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}
body, html {
  height: 100%;
  width: 100%;
  font-family: Arial, sans-serif;
}
body {
  background: url('background.png') no-repeat center center fixed;
  background-size: cover;
}
.overlay {
  position: absolute;
  bottom: 40px;
  width: 100%;
  text-align: center;
}
.buttons a {
  display: inline-block;
  margin: 0 10px;
  padding: 15px 25px;
  font-size: 18px;
  color: #00f0ff;
  border: 2px solid #00f0ff;
  border-radius: 12px;
  text-decoration: none;
  background-color: rgba(0, 0, 0, 0.5);
  transition: 0.3s;
}
.buttons a:hover {
  background-color: #00f0ff;
  color: #000;
}