.container {
  width: 40%;
  margin:0 auto;
  padding: 20px;
}
/* Navigation style */
.header {
  position: sticky;
  top:0;
  background: #fff;
  padding:25px;
}
.title {
  text-align: center;
}
ul {
 list-style: none;
 padding: 0;
 text-align: center;
}

ul li {
  display: inline-block;
  border:1px solid black;
  margin-left: 25px;
}

ul li:first-child {
  margin-left: 0;
}

ul li a {
  display: block;
  padding: 12px 25px;
  color: black;
  text-decoration: none;
}