adding php code to the head of a template

<?php
    $hour = date('H');
    if($h < 8 || $h >= 20) {
      $css = 'background: transparent url(/assets/templates/main/images/bg_container_night.gif) no-repeat 100% 5px';
    } elseif ($h >=17) {
      $css = 'background: transparent url(/assets/templates/main/images/bg_container_cloud.gif) no-repeat 100% 5px';
    } else {
      $css = 'background: transparent url(/assets/templates/main/images/bg_container.gif) no-repeat 100% 5px';
    }
    echo '<style type="text/css">'.$css.'</style>';
?>