BEM

<nav class="nav-bar">

    <img src="" class="nav-bar__logo">

   <ul class="nav-bar-content">

    <li class="nav-bar__item">One</li>

    <li class="nav-bar__item">Two</li>

    <li class="nav-bar__item">Three</li>

   </ul>

  </nav>

  <header class="header"></header>