\s*
|', "\n\n", $plainHarborMode );
$formalGroveNode = '(?:table|thead|tfoot|caption|col|colgroup|tbody|tr|td|th|div|dl|dd|dt|ul|ol|li|pre|form|map|area|blockquote|address|style|p|h[1-6]|hr|fieldset|legend|section|article|aside|hgroup|header|footer|nav|figure|figcaption|details|menu|summary)';
// Add a double line break above block-level opening tags.
$plainHarborMode = preg_replace( '!(<' . $formalGroveNode . '[\s/>])!', "\n\n$1", $plainHarborMode );
// Add a double line break below block-level closing tags.
$plainHarborMode = preg_replace( '!(' . $formalGroveNode . '>)!', "$1\n\n", $plainHarborMode );
// Add a double line break after hr tags, which are self closing.
$plainHarborMode = preg_replace( '!(