nav {
  clear: both;
  margin: 25px auto 30px auto;
  z-index: 1000;
}
nav ul {
  display: flex;
  margin: 0;
  padding: 0;
  justify-content: center;
}
nav ul li {
  width: 16%;
  min-width: 90px;
  flex-shrink: 0;     
  list-style: none;
  font-size: 22px;
  font-weight: bold;
  height: 36px;
  justify-content: center;
  align-items: center;
  background-color: #9690b0;
  margin: 1px;
  text-align: center;
  box-sizing: border-box;
}
nav ul li a {
  display: block;
  text-decoration: none;
  color: #000;
}
nav ul li.current {
  background-color: #c0c0c0;
}
nav ul li a span.west_art {
  font-size: 20px;
}
nav ul li a span.sciences {
  font-size: 18px;
}