<header>
  <ul class="navigation">
    <li><a>Home</a></li>
    <li><a>Articles</a></li>
    <li><a>Solutions</a></li>
    <li><a>About</a></li>
    <li><a>Contact</a></li>
  </ul>
</header>
body {
  background-color: #eee;
  color: #555;
  font-size: 1.1em;
  font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif;
}

header {
  background-color: white;
}

.navigation {
  list-style: none;
  margin: 0;
  padding: 0;
  background-color: #594255;
  color: #eee;
  -webkit-display: -webkit-box;
  -webkit-display: -webkit-flex;
  display: -webkit-box;
  display: -ms-flexbox;
  display: flex;
  -webkit-justify-content: space-between;
  -webkit-box-pack: justify;
  -ms-flex-pack: justify;
  justify-content: space-between;
}

li {
  padding: 1em;
}

@media screen and (max-width: 430px) {
  .navigation {
    -webkit-flex-direction: column;
    -webkit-box-orient: vertical;
    -webkit-box-direction: normal;
    -ms-flex-direction: column;
    flex-direction: column;
  }
  li {
    text-align: center;
  }
}