.topnav {
  position: relative;
  overflow: hidden;
}

.topnav a {
  float: left;

  text-align: center;
  padding: 14px 16px;
  text-decoration: none;
}

.topnav-centered a {
  float: none;
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
}

.topnav-right {
  float: right;
}

/* Responsive navigation menu (for mobile devices) */
@media screen and (max-width: 600px) {
  .topnav a,
  .topnav-right {
    float: none;
    display: block;
  }

  .topnav-centered a {
    position: relative;
    top: 0;
    left: 0;
    transform: none;
  }
}