style.css

body {
  background-image: url("background.png");
  font-family: 'Open Sans', sans-serif;
  color: #19222a;
  text-align: center;
  margin: 0;
}

button {
  font-size: 20px;
  margin: 20px;
}

.navigation {
  width: 700px;
  list-style: none;
  padding: 0;
  margin: 0 auto;
}

.navigation a {
  display: block;
  background-color: #ffffff;
  text-decoration: none;
  padding: 10px;
}

.navigation a:hover {
  background-color: #dcdcdc;
}

.navigation > li > a {
  border-radius: 5px;
  margin-top: 3px;
}

.navigation > .itemselected > a {
  color: #ffffff;
  background-color: #0088cc;
}