header {
  background-color: rgba(0, 0, 0, 0.2);
  overflow: hidden;
  z-index: -1;
}
header .logo {
  float: left;
  margin: 5px 0 5px 5px;
}
header .logo img {
  width: 135px;
}
header nav {
  float: right;
}
header ul {
  display: table;
  list-style-type: none;
}

header ul li {
  display: inline-block;
  width: 150px;
}

header li a {
  color: white;
  display: block;
  padding: 42px 0;
  text-align: center;
  text-decoration: none;
}

@media screen and (max-width: 900px) {
  header .logo img {
    width: 100px;
  }
  header ul li {
    width: 100px;
  }
  header li a {
    padding-bottom: 30px;
    padding-top: 30px;
  }
}

@media screen and (max-width: 600px) {
  header .logo img {
    width: 80px;
  }
  header ul li {
    width: 80px;
  }
  header li a {
    padding-bottom: 24px;
    padding-top: 24px;
  }
}