I am working on a CSS only psd conversion and I need to center the banner text vertically in the middle of the banner image. Any suggestions how to accomplish without using flexbox and grid?
header {
    background-image: url(../assets/main-banner.png);
    background-size: cover;
    background-repeat: no-repeat;
    /* viewport (screen height), the el is now taking 90% of the browser height */
    /* We are doing this since the <header> doesn't have a ton
  of content and we want to be able to see the background image. */
    height: 90vh;
    padding-top: 30px;
}
h1 {
  font-family: 'Iceberg', cursive;
  font-size: 8rem;
  text-align: center;;
  line-height: 80px;
  text-transform: uppercase;
}
header h2 {
  font-family: 'Montserrat', sans-serif;
  font-size: 3.5rem;
  text-align: center;
  text-transform: none;
  background-color: rgb(146, 0, 255);
}<header class="clearfix">
  <div class="wrapper">
  <!-- Navigation STARTS-->
    <nav class="main-menu">
      <ul>
        <li><a href="">Home</a></li>
        <li><a href="">About</a></li>
        <li><a href="">Blog</a></li>
        <li><a href="">Contact</a></li>
      </ul>
    </nav>
    <!-- Navigation ENDS-->
    <div class="banner-content">
      <h1>Thunder<br>Force<br> Stadium</h1>
      <h2>presented by hot cops</h2>
    </div>
  </div>
</header> 
    