Miscellany

<style type="text/css">
.post_one {
  background: #ff0000;
}

.post_two {
  background: #000000;
}
</style>

while ( have_posts()......

  if ( $post_class == 'post_one' ) {
    $post_class = 'post_two';
  }
  else {
    $post_class = 'post_two';
  }

  <div class="<?php echo $post_class; ?>">
    <post content here>
  </div>




endwhile;