.header {
  position: relative;
  height: 110px;
  padding: 0 calc((100% - 1000px)/2);
  background-color: rgba(0, 0, 0, 0.5);
  padding: 10px auto;
  display: flex;
  justify-content: space-between;
  line-height: 110px;
}
.header .nav {
  display: flex;
  align-items: center;
  height: 75%;
  font-size: 16px;
  font-weight: 450;
  color: white;
}
.header .nav a {
  display: inline-block;
  width: 100px;
  height: 100%;
  color: white;
  text-align: center;
}
.header .nav li {
  height: 100%;
  margin: 0 20px;
}