Basic header

<header class="header">
  <div class="header__wrapper">
    <div class="header__row header__row--user-menu">
    Row for a user menu
    </div>
    <div class="header__row">
    Row for logo/search/etc
    </div>
    <div class="header__row header__row--main-menu">
    Row for the main horizontal menu
    </div>
    <div class="header__row header__row--mobile">
    Row mobile items - menu button/logo/user button
    </div>
    <div class="header__row header__row--mobile">
    Row mobile search
    </div>
    <div class="responsive-nav" id="responsive-nav">
    Add mobile responsive nav here
    </div>
  </div>
</header>