header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 1em;
  background-color: #333;
  color: #fff;
}

header a {
  color: #fff;
  text-decoration: none;
  padding: 0.5em;
  white-space: nowrap;
}

/*header a:hover {*/
/*  background-color: #444;*/
/*  border-radius: 5px;*/
/*}*/

@media (max-width: 600px) {
  header {
    flex-wrap: wrap;
    justify-content: space-around;
  }

  header a {
    flex-grow: 1;
    text-align: center;
  }
}