nav-height = 64 + 3*2px

#header
  height nav-height
  padding 50px 0
  nav
    font 1.5em font-title
    line-height nav-height
    ul
      list-style none
      text-align center
      li
        margin 0 50px
        display inline-block

      a
        color #fff
        opacity 0.7
        transition 0.3s
        &:hover
          opacity 1