JSFiddle - React, Tailwind, and code Playground

HTML

<header id="masthead" class="site-header" role="banner">
      <div class="header-shadow"></div>
      <hgroup></hgroup>
      <nav role="navigation" class="site-navigation main-navigation">

      </nav><!-- .site-navigation .main-navigation -->
</header><!-- #masthead .site-header -->

CSS

.header-shadow{
    background-image: url('../images/header-shade.jpg');
    background-color:red;
    height:50px;
}