header {
  background-color: #222;
  padding: 25px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

header h1 {
  font-size: 2.8em;
  font-weight: 200;
}

header nav {
  display: flex;
  align-items: center;
}

header nav a {
  margin-right: 2.8em;
  font-size: 1.2em;
}

header h1,
a {
  color: #00e0ff;
}

/*Atenção na semântica aqui*/
header nav a:hover {
  color: #fff;
}