From de46b4527d0679351e0ebdebb03ab25389cd026e Mon Sep 17 00:00:00 2001
From: Jake Oehler Morrison <jake.morrison@automattic.com>
Date: Wed, 11 Apr 2018 17:17:27 +0100
Subject: [PATCH 1/3] Add styles to email content from a dynamic stylesheet

Follow's WC's lead on this.
---
 ...ass-wp-job-manager-email-notifications.php |   50 +
 lib/emogrifier/class-emogrifier.php           | 1557 +++++++++++++++++
 templates/emails/email-styles.php             |   38 +
 3 files changed, 1645 insertions(+)
 create mode 100644 lib/emogrifier/class-emogrifier.php
 create mode 100644 templates/emails/email-styles.php

diff --git a/includes/class-wp-job-manager-email-notifications.php b/includes/class-wp-job-manager-email-notifications.php
index 0932dd0a5..738db322e 100644
--- a/includes/class-wp-job-manager-email-notifications.php
+++ b/includes/class-wp-job-manager-email-notifications.php
@@ -98,6 +98,9 @@ public static function _lazy_init() {
 		add_action( 'shutdown', array( __CLASS__, '_send_deferred_notifications' ) );
 
 		include_once JOB_MANAGER_PLUGIN_DIR . '/includes/emails/class-wp-job-manager-email-admin-new-job.php';
+		if ( ! class_exists( 'Emogrifier' ) && class_exists( 'DOMDocument' ) ) {
+			include_once JOB_MANAGER_PLUGIN_DIR . '/lib/emogrifier/class-emogrifier.php';
+		}
 	}
 
 	/**
@@ -304,9 +307,56 @@ private static function get_email_content( $email_notification_key, $args ) {
 		do_action( 'job_manager_email_footer', $email_notification_key, $args, $plain_text );
 
 		$content = ob_get_clean();
+		if ( ! $plain_text ) {
+			$content = self::inject_styles( $content );
+		}
+
+		/**
+		 * Filter the content of the email.
+		 *
+		 * @since 1.31.0
+		 *
+		 * @param string $content                Email content.
+		 * @param string $email_notification_key Unique email notification key.
+		 * @param array  $args                   Arguments passed for generating email.
+		 * @param bool   $plain_text             True if sending plain text email.
+		 */
+		return apply_filters( 'job_manager_email_content', $content, $email_notification_key, $args, $plain_text );
+	}
+
+	/**
+	 * Inject inline styles into email content.
+	 *
+	 * @param string $content
+	 * @return string
+	 */
+	private static function inject_styles( $content ) {
+		if ( class_exists( 'Emogrifier' ) ) {
+			try {
+				$emogrifier = new Emogrifier( $content, self::get_styles() );
+				$content    = $emogrifier->emogrify();
+			} catch ( Exception $e ) {
+				trigger_error( 'Unable to inject styles into email notification: ' . $e->getMessage() );
+			}
+		}
 		return $content;
 	}
 
+	/**
+	 * Gets the CSS styles to be used in email notifications.
+	 *
+	 * @return bool|string
+	 */
+	private static function get_styles() {
+		$email_styles_template = locate_job_manager_template( self::get_template_file_name( 'email-styles' ) );
+		if ( ! file_exists( $email_styles_template ) ) {
+			return false;
+		}
+		ob_start();
+		include $email_styles_template;
+		return ob_get_clean();
+	}
+
 	/**
 	 * Checks if a particular notification is enabled or not.
 	 *
diff --git a/lib/emogrifier/class-emogrifier.php b/lib/emogrifier/class-emogrifier.php
new file mode 100644
index 000000000..6eaea21c1
--- /dev/null
+++ b/lib/emogrifier/class-emogrifier.php
@@ -0,0 +1,1557 @@
+<?php
+/**
+ * This class provides functions for converting CSS styles into inline style attributes in your HTML code.
+ *
+ * For more information, please see the README.md file.
+ *
+ * @version 1.2.0
+ *
+ * @author Cameron Brooks
+ * @author Jaime Prado
+ * @author Oliver Klee <typo3-coding@oliverklee.de>
+ * @author Roman Ožana <ozana@omdesign.cz>
+ * @author Sander Kruger <s.kruger@invessel.com>
+ *
+ * @see https://raw.githubusercontent.com/MyIntervals/emogrifier/V1.2.0/Classes/Emogrifier.php
+ */
+// @codingStandardsIgnoreFile
+class Emogrifier
+{
+	/**
+	 * @var int
+	 */
+	const CACHE_KEY_CSS = 0;
+
+	/**
+	 * @var int
+	 */
+	const CACHE_KEY_SELECTOR = 1;
+
+	/**
+	 * @var int
+	 */
+	const CACHE_KEY_XPATH = 2;
+
+	/**
+	 * @var int
+	 */
+	const CACHE_KEY_CSS_DECLARATIONS_BLOCK = 3;
+
+	/**
+	 * @var int
+	 */
+	const CACHE_KEY_COMBINED_STYLES = 4;
+
+	/**
+	 * for calculating nth-of-type and nth-child selectors
+	 *
+	 * @var int
+	 */
+	const INDEX = 0;
+
+	/**
+	 * for calculating nth-of-type and nth-child selectors
+	 *
+	 * @var int
+	 */
+	const MULTIPLIER = 1;
+
+	/**
+	 * @var string
+	 */
+	const ID_ATTRIBUTE_MATCHER = '/(\\w+)?\\#([\\w\\-]+)/';
+
+	/**
+	 * @var string
+	 */
+	const CLASS_ATTRIBUTE_MATCHER = '/(\\w+|[\\*\\]])?((\\.[\\w\\-]+)+)/';
+
+	/**
+	 * @var string
+	 */
+	const CONTENT_TYPE_META_TAG = '<meta http-equiv="Content-Type" content="text/html; charset=utf-8">';
+
+	/**
+	 * @var string
+	 */
+	const DEFAULT_DOCUMENT_TYPE = '<!DOCTYPE html>';
+
+	/**
+	 * @var string
+	 */
+	private $html = '';
+
+	/**
+	 * @var string
+	 */
+	private $css = '';
+
+	/**
+	 * @var bool[]
+	 */
+	private $excludedSelectors = array();
+
+	/**
+	 * @var string[]
+	 */
+	private $unprocessableHtmlTags = array( 'wbr' );
+
+	/**
+	 * @var bool[]
+	 */
+	private $allowedMediaTypes = array( 'all' => true, 'screen' => true, 'print' => true );
+
+	/**
+	 * @var mixed[]
+	 */
+	private $caches = array(
+		self::CACHE_KEY_CSS => array(),
+		self::CACHE_KEY_SELECTOR => array(),
+		self::CACHE_KEY_XPATH => array(),
+		self::CACHE_KEY_CSS_DECLARATIONS_BLOCK => array(),
+		self::CACHE_KEY_COMBINED_STYLES => array(),
+	);
+
+	/**
+	 * the visited nodes with the XPath paths as array keys
+	 *
+	 * @var \DOMElement[]
+	 */
+	private $visitedNodes = array();
+
+	/**
+	 * the styles to apply to the nodes with the XPath paths as array keys for the outer array
+	 * and the attribute names/values as key/value pairs for the inner array
+	 *
+	 * @var string[][]
+	 */
+	private $styleAttributesForNodes = array();
+
+	/**
+	 * Determines whether the "style" attributes of tags in the the HTML passed to this class should be preserved.
+	 * If set to false, the value of the style attributes will be discarded.
+	 *
+	 * @var bool
+	 */
+	private $isInlineStyleAttributesParsingEnabled = true;
+
+	/**
+	 * Determines whether the <style> blocks in the HTML passed to this class should be parsed.
+	 *
+	 * If set to true, the <style> blocks will be removed from the HTML and their contents will be applied to the HTML
+	 * via inline styles.
+	 *
+	 * If set to false, the <style> blocks will be left as they are in the HTML.
+	 *
+	 * @var bool
+	 */
+	private $isStyleBlocksParsingEnabled = true;
+
+	/**
+	 * Determines whether elements with the `display: none` property are
+	 * removed from the DOM.
+	 *
+	 * @var bool
+	 */
+	private $shouldKeepInvisibleNodes = true;
+
+	/**
+	 * @var string[]
+	 */
+	private $xPathRules = array(
+		// child
+		'/\\s*>\\s*/'                              => '/',
+		// adjacent sibling
+		'/\\s+\\+\\s+/'                            => '/following-sibling::*[1]/self::',
+		// descendant
+		'/\\s+(?=.*[^\\]]{1}$)/'                   => '//',
+		// :first-child
+		'/([^\\/]+):first-child/i'                 => '*[1]/self::\\1',
+		// :last-child
+		'/([^\\/]+):last-child/i'                  => '*[last()]/self::\\1',
+		// attribute only
+		'/^\\[(\\w+|\\w+\\=[\'"]?\\w+[\'"]?)\\]/'  => '*[@\\1]',
+		// attribute
+		'/(\\w)\\[(\\w+)\\]/'                      => '\\1[@\\2]',
+		// exact attribute
+		'/(\\w)\\[(\\w+)\\=[\'"]?([\\w\\s]+)[\'"]?\\]/' => '\\1[@\\2="\\3"]',
+		// element attribute~=
+		'/([\\w\\*]+)\\[(\\w+)[\\s]*\\~\\=[\\s]*[\'"]?([\\w-_\\/]+)[\'"]?\\]/'
+		=> '\\1[contains(concat(" ", @\\2, " "), concat(" ", "\\3", " "))]',
+		// element attribute^=
+		'/([\\w\\*]+)\\[(\\w+)[\\s]*\\^\\=[\\s]*[\'"]?([\\w-_\\/]+)[\'"]?\\]/' => '\\1[starts-with(@\\2, "\\3")]',
+		// element attribute*=
+		'/([\\w\\*]+)\\[(\\w+)[\\s]*\\*\\=[\\s]*[\'"]?([\\w-_\\s\\/:;]+)[\'"]?\\]/' => '\\1[contains(@\\2, "\\3")]',
+		// element attribute$=
+		'/([\\w\\*]+)\\[(\\w+)[\\s]*\\$\\=[\\s]*[\'"]?([\\w-_\\s\\/]+)[\'"]?\\]/'
+		=> '\\1[substring(@\\2, string-length(@\\2) - string-length("\\3") + 1) = "\\3"]',
+		// element attribute|=
+		'/([\\w\\*]+)\\[(\\w+)[\\s]*\\|\\=[\\s]*[\'"]?([\\w-_\\s\\/]+)[\'"]?\\]/'
+		=> '\\1[@\\2="\\3" or starts-with(@\\2, concat("\\3", "-"))]',
+	);
+
+	/**
+	 * Determines whether CSS styles that have an equivalent HTML attribute
+	 * should be mapped and attached to those elements.
+	 *
+	 * @var bool
+	 */
+	private $shouldMapCssToHtml = false;
+
+	/**
+	 * This multi-level array contains simple mappings of CSS properties to
+	 * HTML attributes. If a mapping only applies to certain HTML nodes or
+	 * only for certain values, the mapping is an object with a whitelist
+	 * of nodes and values.
+	 *
+	 * @var mixed[][]
+	 */
+	private $cssToHtmlMap = array(
+		'background-color' => array(
+			'attribute' => 'bgcolor',
+		),
+		'text-align' => array(
+			'attribute' => 'align',
+			'nodes' => array('p', 'div', 'td'),
+			'values' => array('left', 'right', 'center', 'justify'),
+		),
+		'float' => array(
+			'attribute' => 'align',
+			'nodes' => array('table', 'img'),
+			'values' => array('left', 'right'),
+		),
+		'border-spacing' => array(
+			'attribute' => 'cellspacing',
+			'nodes' => array('table'),
+		),
+	);
+
+	public static $_media = '';
+
+	/**
+	 * The constructor.
+	 *
+	 * @param string $html the HTML to emogrify, must be UTF-8-encoded
+	 * @param string $css the CSS to merge, must be UTF-8-encoded
+	 */
+	public function __construct($html = '', $css = '')
+	{
+		$this->setHtml($html);
+		$this->setCss($css);
+	}
+
+	/**
+	 * The destructor.
+	 */
+	public function __destruct()
+	{
+		$this->purgeVisitedNodes();
+	}
+
+	/**
+	 * Sets the HTML to emogrify.
+	 *
+	 * @param string $html the HTML to emogrify, must be UTF-8-encoded
+	 *
+	 * @return void
+	 */
+	public function setHtml($html)
+	{
+		$this->html = $html;
+	}
+
+	/**
+	 * Sets the CSS to merge with the HTML.
+	 *
+	 * @param string $css the CSS to merge, must be UTF-8-encoded
+	 *
+	 * @return void
+	 */
+	public function setCss($css)
+	{
+		$this->css = $css;
+	}
+
+	/**
+	 * Applies $this->css to $this->html and returns the HTML with the CSS
+	 * applied.
+	 *
+	 * This method places the CSS inline.
+	 *
+	 * @return string
+	 *
+	 * @throws \BadMethodCallException
+	 */
+	public function emogrify()
+	{
+		if ($this->html === '') {
+			throw new BadMethodCallException('Please set some HTML first before calling emogrify.', 1390393096);
+		}
+
+		self::$_media = ''; // reset.
+
+		$xmlDocument = $this->createXmlDocument();
+		$this->process($xmlDocument);
+
+		return $xmlDocument->saveHTML();
+	}
+
+	/**
+	 * Applies $this->css to $this->html and returns only the HTML content
+	 * within the <body> tag.
+	 *
+	 * This method places the CSS inline.
+	 *
+	 * @return string
+	 *
+	 * @throws \BadMethodCallException
+	 */
+	public function emogrifyBodyContent()
+	{
+		if ($this->html === '') {
+			throw new BadMethodCallException('Please set some HTML first before calling emogrify.', 1390393096);
+		}
+
+		$xmlDocument = $this->createXmlDocument();
+		$this->process($xmlDocument);
+
+		$innerDocument = new DOMDocument();
+		foreach ($xmlDocument->documentElement->getElementsByTagName('body')->item(0)->childNodes as $childNode) {
+			$innerDocument->appendChild($innerDocument->importNode($childNode, true));
+		}
+
+		return html_entity_decode($innerDocument->saveHTML());
+	}
+
+	/**
+	 * Applies $this->css to $xmlDocument.
+	 *
+	 * This method places the CSS inline.
+	 *
+	 * @param \DOMDocument $xmlDocument
+	 *
+	 * @return void
+	 *
+	 * @throws \InvalidArgumentException
+	 */
+	protected function process(DOMDocument $xmlDocument)
+	{
+		$xPath = new DOMXPath($xmlDocument);
+		$this->clearAllCaches();
+
+		// Before be begin processing the CSS file, parse the document and normalize all existing CSS attributes.
+		// This changes 'DISPLAY: none' to 'display: none'.
+		// We wouldn't have to do this if DOMXPath supported XPath 2.0.
+		// Also store a reference of nodes with existing inline styles so we don't overwrite them.
+		$this->purgeVisitedNodes();
+
+		set_error_handler(array($this, 'handleXpathError'), E_WARNING);
+
+		$nodesWithStyleAttributes = $xPath->query('//*[@style]');
+		if ($nodesWithStyleAttributes !== false) {
+			/** @var \DOMElement $node */
+			foreach ($nodesWithStyleAttributes as $node) {
+				if ($this->isInlineStyleAttributesParsingEnabled) {
+					$this->normalizeStyleAttributes($node);
+				} else {
+					$node->removeAttribute('style');
+				}
+			}
+		}
+
+		// grab any existing style blocks from the html and append them to the existing CSS
+		// (these blocks should be appended so as to have precedence over conflicting styles in the existing CSS)
+		$allCss = $this->css;
+
+		if ($this->isStyleBlocksParsingEnabled) {
+			$allCss .= $this->getCssFromAllStyleNodes($xPath);
+		}
+
+		$cssParts = $this->splitCssAndMediaQuery($allCss);
+		$excludedNodes = $this->getNodesToExclude($xPath);
+		$cssRules = $this->parseCssRules($cssParts['css']);
+		foreach ($cssRules as $cssRule) {
+			// query the body for the xpath selector
+			$nodesMatchingCssSelectors = $xPath->query($this->translateCssToXpath($cssRule['selector']));
+			// ignore invalid selectors
+			if ($nodesMatchingCssSelectors === false) {
+				continue;
+			}
+
+			/** @var \DOMElement $node */
+			foreach ($nodesMatchingCssSelectors as $node) {
+				if (in_array($node, $excludedNodes, true)) {
+					continue;
+				}
+
+				// if it has a style attribute, get it, process it, and append (overwrite) new stuff
+				if ($node->hasAttribute('style')) {
+					// break it up into an associative array
+					$oldStyleDeclarations = $this->parseCssDeclarationsBlock($node->getAttribute('style'));
+				} else {
+					$oldStyleDeclarations = array();
+				}
+				$newStyleDeclarations = $this->parseCssDeclarationsBlock($cssRule['declarationsBlock']);
+				if ($this->shouldMapCssToHtml) {
+					$this->mapCssToHtmlAttributes($newStyleDeclarations, $node);
+				}
+				$node->setAttribute(
+					'style',
+					$this->generateStyleStringFromDeclarationsArrays($oldStyleDeclarations, $newStyleDeclarations)
+				);
+			}
+		}
+
+		restore_error_handler();
+
+		if ($this->isInlineStyleAttributesParsingEnabled) {
+			$this->fillStyleAttributesWithMergedStyles();
+		}
+
+		if ($this->shouldKeepInvisibleNodes) {
+			$this->removeInvisibleNodes($xPath);
+		}
+
+		$this->copyCssWithMediaToStyleNode($xmlDocument, $xPath, $cssParts['media']);
+	}
+
+	/**
+	 * Applies $styles to $node.
+	 *
+	 * This method maps CSS styles to HTML attributes and adds those to the
+	 * node.
+	 *
+	 * @param string[] $styles the new CSS styles taken from the global styles to be applied to this node
+	 * @param \DOMNode $node   node to apply styles to
+	 *
+	 * @return void
+	 */
+	private function mapCssToHtmlAttributes(array $styles, DOMNode $node)
+	{
+		foreach ($styles as $property => $value) {
+			// Strip !important indicator
+			$value = trim(str_replace('!important', '', $value));
+			$this->mapCssToHtmlAttribute($property, $value, $node);
+		}
+	}
+
+	/**
+	 * Tries to apply the CSS style to $node as an attribute.
+	 *
+	 * This method maps a CSS rule to HTML attributes and adds those to the node.
+	 *
+	 * @param string $property the name of the CSS property to map
+	 * @param string $value    the value of the style rule to map
+	 * @param \DOMNode $node   node to apply styles to
+	 *
+	 * @return void
+	 */
+	private function mapCssToHtmlAttribute($property, $value, DOMNode $node)
+	{
+		if (!$this->mapSimpleCssProperty($property, $value, $node)) {
+			$this->mapComplexCssProperty($property, $value, $node);
+		}
+	}
+
+	/**
+	 * Looks up the CSS property in the mapping table and maps it if it matches the conditions.
+	 *
+	 * @param string $property the name of the CSS property to map
+	 * @param string $value    the value of the style rule to map
+	 * @param \DOMNode $node   node to apply styles to
+	 *
+	 * @return bool true if the property cab be mapped using the simple mapping table
+	 */
+	private function mapSimpleCssProperty($property, $value, DOMNode $node)
+	{
+		if (!isset($this->cssToHtmlMap[$property])) {
+			return false;
+		}
+
+		$mapping = $this->cssToHtmlMap[$property];
+		$nodesMatch = !isset($mapping['nodes']) || in_array($node->nodeName, $mapping['nodes'], true);
+		$valuesMatch = !isset($mapping['values']) || in_array($value, $mapping['values'], true);
+		if (!$nodesMatch || !$valuesMatch) {
+			return false;
+		}
+
+		$node->setAttribute($mapping['attribute'], $value);
+
+		return true;
+	}
+
+	/**
+	 * Maps CSS properties that need special transformation to an HTML attribute.
+	 *
+	 * @param string $property the name of the CSS property to map
+	 * @param string $value    the value of the style rule to map
+	 * @param \DOMNode $node   node to apply styles to
+	 *
+	 * @return void
+	 */
+	private function mapComplexCssProperty($property, $value, DOMNode $node)
+	{
+		$nodeName = $node->nodeName;
+		$isTable = $nodeName === 'table';
+		$isImage = $nodeName === 'img';
+		$isTableOrImage = $isTable || $isImage;
+
+		switch ($property) {
+			case 'background':
+				// Parse out the color, if any
+				$styles = explode(' ', $value);
+				$first = $styles[0];
+				if (!is_numeric(substr($first, 0, 1)) && substr($first, 0, 3) !== 'url') {
+					// This is not a position or image, assume it's a color
+					$node->setAttribute('bgcolor', $first);
+				}
+				break;
+			case 'width':
+				// intentional fall-through
+			case 'height':
+				// Only parse values in px and %, but not values like "auto".
+				if (preg_match('/^\d+(px|%)$/', $value)) {
+					// Remove 'px'. This regex only conserves numbers and %
+					$number = preg_replace('/[^0-9.%]/', '', $value);
+					$node->setAttribute($property, $number);
+				}
+				break;
+			case 'margin':
+				if ($isTableOrImage) {
+					$margins = $this->parseCssShorthandValue($value);
+					if ($margins['left'] === 'auto' && $margins['right'] === 'auto') {
+						$node->setAttribute('align', 'center');
+					}
+				}
+				break;
+			case 'border':
+				if ($isTableOrImage) {
+					if ($value === 'none' || $value === '0') {
+						$node->setAttribute('border', '0');
+					}
+				}
+				break;
+			default:
+		}
+	}
+
+	/**
+	 * Parses a shorthand CSS value and splits it into individual values
+	 *
+	 * @param string $value a string of CSS value with 1, 2, 3 or 4 sizes
+	 *                      For example: padding: 0 auto;
+	 *                      '0 auto' is split into top: 0, left: auto, bottom: 0,
+	 *                      right: auto.
+	 *
+	 * @return string[] an array of values for top, right, bottom and left (using these as associative array keys)
+	 */
+	private function parseCssShorthandValue($value)
+	{
+		$values = preg_split('/\\s+/', $value);
+
+		$css = array();
+		$css['top'] = $values[0];
+		$css['right'] = (count($values) > 1) ? $values[1] : $css['top'];
+		$css['bottom'] = (count($values) > 2) ? $values[2] : $css['top'];
+		$css['left'] = (count($values) > 3) ? $values[3] : $css['right'];
+
+		return $css;
+	}
+
+	/**
+	 * Extracts and parses the individual rules from a CSS string.
+	 *
+	 * @param string $css a string of raw CSS code
+	 *
+	 * @return string[][] an array of string sub-arrays with the keys
+	 *         "selector" (the CSS selector(s), e.g., "*" or "h1"),
+	 *         "declarationsBLock" (the semicolon-separated CSS declarations for that selector(s),
+	 *         e.g., "color: red; height: 4px;"),
+	 *         and "line" (the line number e.g. 42)
+	 */
+	private function parseCssRules($css)
+	{
+		$cssKey = md5($css);
+		if (!isset($this->caches[self::CACHE_KEY_CSS][$cssKey])) {
+			// process the CSS file for selectors and definitions
+			preg_match_all('/(?:^|[\\s^{}]*)([^{]+){([^}]*)}/mis', $css, $matches, PREG_SET_ORDER);
+
+			$cssRules = array();
+			/** @var string[] $cssRule */
+			foreach ($matches as $key => $cssRule) {
+				$cssDeclaration = trim($cssRule[2]);
+				if ($cssDeclaration === '') {
+					continue;
+				}
+
+				$selectors = explode(',', $cssRule[1]);
+				foreach ($selectors as $selector) {
+					// don't process pseudo-elements and behavioral (dynamic) pseudo-classes;
+					// only allow structural pseudo-classes
+					$hasPseudoElement = strpos($selector, '::') !== false;
+					$hasAnyPseudoClass = (bool) preg_match('/:[a-zA-Z]/', $selector);
+					$hasSupportedPseudoClass = (bool) preg_match('/:\\S+\\-(child|type\\()/i', $selector);
+					if ($hasPseudoElement || ($hasAnyPseudoClass && !$hasSupportedPseudoClass)) {
+						continue;
+					}
+
+					$cssRules[] = array(
+						'selector' => trim($selector),
+						'declarationsBlock' => $cssDeclaration,
+						// keep track of where it appears in the file, since order is important
+						'line' => $key,
+					);
+				}
+			}
+
+			usort($cssRules, array($this, 'sortBySelectorPrecedence'));
+
+			$this->caches[self::CACHE_KEY_CSS][$cssKey] = $cssRules;
+		}
+
+		return $this->caches[self::CACHE_KEY_CSS][$cssKey];
+	}
+
+	/**
+	 * Disables the parsing of inline styles.
+	 *
+	 * @return void
+	 */
+	public function disableInlineStyleAttributesParsing()
+	{
+		$this->isInlineStyleAttributesParsingEnabled = false;
+	}
+
+	/**
+	 * Disables the parsing of <style> blocks.
+	 *
+	 * @return void
+	 */
+	public function disableStyleBlocksParsing()
+	{
+		$this->isStyleBlocksParsingEnabled = false;
+	}
+
+	/**
+	 * Disables the removal of elements with `display: none` properties.
+	 *
+	 * @return void
+	 */
+	public function disableInvisibleNodeRemoval()
+	{
+		$this->shouldKeepInvisibleNodes = false;
+	}
+
+	/**
+	 * Enables the attachment/override of HTML attributes for which a
+	 * corresponding CSS property has been set.
+	 *
+	 * @return void
+	 */
+	public function enableCssToHtmlMapping()
+	{
+		$this->shouldMapCssToHtml = true;
+	}
+
+	/**
+	 * Clears all caches.
+	 *
+	 * @return void
+	 */
+	private function clearAllCaches()
+	{
+		$this->clearCache(self::CACHE_KEY_CSS);
+		$this->clearCache(self::CACHE_KEY_SELECTOR);
+		$this->clearCache(self::CACHE_KEY_XPATH);
+		$this->clearCache(self::CACHE_KEY_CSS_DECLARATIONS_BLOCK);
+		$this->clearCache(self::CACHE_KEY_COMBINED_STYLES);
+	}
+
+	/**
+	 * Clears a single cache by key.
+	 *
+	 * @param int $key the cache key, must be CACHE_KEY_CSS, CACHE_KEY_SELECTOR, CACHE_KEY_XPATH
+	 *                 or CACHE_KEY_CSS_DECLARATION_BLOCK
+	 *
+	 * @return void
+	 *
+	 * @throws \InvalidArgumentException
+	 */
+	private function clearCache($key)
+	{
+		$allowedCacheKeys = array(
+			self::CACHE_KEY_CSS,
+			self::CACHE_KEY_SELECTOR,
+			self::CACHE_KEY_XPATH,
+			self::CACHE_KEY_CSS_DECLARATIONS_BLOCK,
+			self::CACHE_KEY_COMBINED_STYLES,
+		);
+		if (!in_array($key, $allowedCacheKeys, true)) {
+			throw new InvalidArgumentException('Invalid cache key: ' . $key, 1391822035);
+		}
+
+		$this->caches[$key] = array();
+	}
+
+	/**
+	 * Purges the visited nodes.
+	 *
+	 * @return void
+	 */
+	private function purgeVisitedNodes()
+	{
+		$this->visitedNodes = array();
+		$this->styleAttributesForNodes = array();
+	}
+
+	/**
+	 * Marks a tag for removal.
+	 *
+	 * There are some HTML tags that DOMDocument cannot process, and it will throw an error if it encounters them.
+	 * In particular, DOMDocument will complain if you try to use HTML5 tags in an XHTML document.
+	 *
+	 * Note: The tags will not be removed if they have any content.
+	 *
+	 * @param string $tagName the tag name, e.g., "p"
+	 *
+	 * @return void
+	 */
+	public function addUnprocessableHtmlTag($tagName)
+	{
+		$this->unprocessableHtmlTags[] = $tagName;
+	}
+
+	/**
+	 * Drops a tag from the removal list.
+	 *
+	 * @param string $tagName the tag name, e.g., "p"
+	 *
+	 * @return void
+	 */
+	public function removeUnprocessableHtmlTag($tagName)
+	{
+		$key = array_search($tagName, $this->unprocessableHtmlTags, true);
+		if ($key !== false) {
+			unset($this->unprocessableHtmlTags[$key]);
+		}
+	}
+
+	/**
+	 * Marks a media query type to keep.
+	 *
+	 * @param string $mediaName the media type name, e.g., "braille"
+	 *
+	 * @return void
+	 */
+	public function addAllowedMediaType($mediaName)
+	{
+		$this->allowedMediaTypes[$mediaName] = true;
+	}
+
+	/**
+	 * Drops a media query type from the allowed list.
+	 *
+	 * @param string $mediaName the tag name, e.g., "braille"
+	 *
+	 * @return void
+	 */
+	public function removeAllowedMediaType($mediaName)
+	{
+		if (isset($this->allowedMediaTypes[$mediaName])) {
+			unset($this->allowedMediaTypes[$mediaName]);
+		}
+	}
+
+	/**
+	 * Adds a selector to exclude nodes from emogrification.
+	 *
+	 * Any nodes that match the selector will not have their style altered.
+	 *
+	 * @param string $selector the selector to exclude, e.g., ".editor"
+	 *
+	 * @return void
+	 */
+	public function addExcludedSelector($selector)
+	{
+		$this->excludedSelectors[$selector] = true;
+	}
+
+	/**
+	 * No longer excludes the nodes matching this selector from emogrification.
+	 *
+	 * @param string $selector the selector to no longer exclude, e.g., ".editor"
+	 *
+	 * @return void
+	 */
+	public function removeExcludedSelector($selector)
+	{
+		if (isset($this->excludedSelectors[$selector])) {
+			unset($this->excludedSelectors[$selector]);
+		}
+	}
+
+	/**
+	 * This removes styles from your email that contain display:none.
+	 * We need to look for display:none, but we need to do a case-insensitive search. Since DOMDocument only
+	 * supports XPath 1.0, lower-case() isn't available to us. We've thus far only set attributes to lowercase,
+	 * not attribute values. Consequently, we need to translate() the letters that would be in 'NONE' ("NOE")
+	 * to lowercase.
+	 *
+	 * @param \DOMXPath $xPath
+	 *
+	 * @return void
+	 */
+	private function removeInvisibleNodes(DOMXPath $xPath)
+	{
+		$nodesWithStyleDisplayNone = $xPath->query(
+			'//*[contains(translate(translate(@style," ",""),"NOE","noe"),"display:none")]'
+		);
+		if ($nodesWithStyleDisplayNone->length === 0) {
+			return;
+		}
+
+		// The checks on parentNode and is_callable below ensure that if we've deleted the parent node,
+		// we don't try to call removeChild on a nonexistent child node
+		/** @var \DOMNode $node */
+		foreach ($nodesWithStyleDisplayNone as $node) {
+			if ($node->parentNode && is_callable(array($node->parentNode, 'removeChild'))) {
+				$node->parentNode->removeChild($node);
+			}
+		}
+	}
+
+	private function normalizeStyleAttributes_callback( $m ) {
+		return strtolower( $m[0] );
+	}
+
+	/**
+	 * Normalizes the value of the "style" attribute and saves it.
+	 *
+	 * @param \DOMElement $node
+	 *
+	 * @return void
+	 */
+	private function normalizeStyleAttributes(DOMElement $node)
+	{
+		$normalizedOriginalStyle = preg_replace_callback(
+			'/[A-z\\-]+(?=\\:)/S',
+			array( $this, 'normalizeStyleAttributes_callback' ),
+			$node->getAttribute('style')
+		);
+
+		// in order to not overwrite existing style attributes in the HTML, we
+		// have to save the original HTML styles
+		$nodePath = $node->getNodePath();
+		if (!isset($this->styleAttributesForNodes[$nodePath])) {
+			$this->styleAttributesForNodes[$nodePath] = $this->parseCssDeclarationsBlock($normalizedOriginalStyle);
+			$this->visitedNodes[$nodePath] = $node;
+		}
+
+		$node->setAttribute('style', $normalizedOriginalStyle);
+	}
+
+	/**
+	 * Merges styles from styles attributes and style nodes and applies them to the attribute nodes
+	 *
+	 * @return void
+	 */
+	private function fillStyleAttributesWithMergedStyles()
+	{
+		foreach ($this->styleAttributesForNodes as $nodePath => $styleAttributesForNode) {
+			$node = $this->visitedNodes[$nodePath];
+			$currentStyleAttributes = $this->parseCssDeclarationsBlock($node->getAttribute('style'));
+			$node->setAttribute(
+				'style',
+				$this->generateStyleStringFromDeclarationsArrays(
+					$currentStyleAttributes,
+					$styleAttributesForNode
+				)
+			);
+		}
+	}
+
+	/**
+	 * This method merges old or existing name/value array with new name/value array
+	 * and then generates a string of the combined style suitable for placing inline.
+	 * This becomes the single point for CSS string generation allowing for consistent
+	 * CSS output no matter where the CSS originally came from.
+	 *
+	 * @param string[] $oldStyles
+	 * @param string[] $newStyles
+	 *
+	 * @return string
+	 */
+	private function generateStyleStringFromDeclarationsArrays(array $oldStyles, array $newStyles)
+	{
+		$combinedStyles = array_merge($oldStyles, $newStyles);
+		$cacheKey = serialize($combinedStyles);
+		if (isset($this->caches[self::CACHE_KEY_COMBINED_STYLES][$cacheKey])) {
+			return $this->caches[self::CACHE_KEY_COMBINED_STYLES][$cacheKey];
+		}
+
+		foreach ($oldStyles as $attributeName => $attributeValue) {
+			if (!isset($newStyles[$attributeName])) {
+				continue;
+			}
+
+			$newAttributeValue = $newStyles[$attributeName];
+			if ($this->attributeValueIsImportant($attributeValue)
+			    && !$this->attributeValueIsImportant($newAttributeValue)
+			) {
+				$combinedStyles[$attributeName] = $attributeValue;
+			}
+		}
+
+		$style = '';
+		foreach ($combinedStyles as $attributeName => $attributeValue) {
+			$style .= strtolower(trim($attributeName)) . ': ' . trim($attributeValue) . '; ';
+		}
+		$trimmedStyle = rtrim($style);
+
+		$this->caches[self::CACHE_KEY_COMBINED_STYLES][$cacheKey] = $trimmedStyle;
+
+		return $trimmedStyle;
+	}
+
+	/**
+	 * Checks whether $attributeValue is marked as !important.
+	 *
+	 * @param string $attributeValue
+	 *
+	 * @return bool
+	 */
+	private function attributeValueIsImportant($attributeValue)
+	{
+		return strtolower(substr(trim($attributeValue), -10)) === '!important';
+	}
+
+	/**
+	 * Applies $css to $xmlDocument, limited to the media queries that actually apply to the document.
+	 *
+	 * @param \DOMDocument $xmlDocument the document to match against
+	 * @param \DOMXPath $xPath
+	 * @param string $css a string of CSS
+	 *
+	 * @return void
+	 */
+	private function copyCssWithMediaToStyleNode(DOMDocument $xmlDocument, DOMXPath $xPath, $css)
+	{
+		if ($css === '') {
+			return;
+		}
+
+		$mediaQueriesRelevantForDocument = array();
+
+		foreach ($this->extractMediaQueriesFromCss($css) as $mediaQuery) {
+			foreach ($this->parseCssRules($mediaQuery['css']) as $selector) {
+				if ($this->existsMatchForCssSelector($xPath, $selector['selector'])) {
+					$mediaQueriesRelevantForDocument[] = $mediaQuery['query'];
+					break;
+				}
+			}
+		}
+
+		$this->addStyleElementToDocument($xmlDocument, implode($mediaQueriesRelevantForDocument));
+	}
+
+	/**
+	 * Extracts the media queries from $css while skipping empty media queries.
+	 *
+	 * @param string $css
+	 *
+	 * @return string[][] numeric array with string sub-arrays with the keys "css" and "query"
+	 */
+	private function extractMediaQueriesFromCss($css)
+	{
+		preg_match_all('/@media\\b[^{]*({((?:[^{}]+|(?1))*)})/', $css, $rawMediaQueries, PREG_SET_ORDER);
+		$parsedQueries = array();
+
+		foreach ($rawMediaQueries as $mediaQuery) {
+			if ($mediaQuery[2] !== '') {
+				$parsedQueries[] = array(
+					'css'   => $mediaQuery[2],
+					'query' => $mediaQuery[0],
+				);
+			}
+		}
+
+		return $parsedQueries;
+	}
+
+	/**
+	 * Checks whether there is at least one matching element for $cssSelector.
+	 *
+	 * @param \DOMXPath $xPath
+	 * @param string $cssSelector
+	 *
+	 * @return bool
+	 */
+	private function existsMatchForCssSelector(DOMXPath $xPath, $cssSelector)
+	{
+		$nodesMatchingSelector = $xPath->query($this->translateCssToXpath($cssSelector));
+
+		return $nodesMatchingSelector !== false && $nodesMatchingSelector->length !== 0;
+	}
+
+	/**
+	 * Returns CSS content.
+	 *
+	 * @param \DOMXPath $xPath
+	 *
+	 * @return string
+	 */
+	private function getCssFromAllStyleNodes(DOMXPath $xPath)
+	{
+		$styleNodes = $xPath->query('//style');
+
+		if ($styleNodes === false) {
+			return '';
+		}
+
+		$css = '';
+		/** @var \DOMNode $styleNode */
+		foreach ($styleNodes as $styleNode) {
+			$css .= "\n\n" . $styleNode->nodeValue;
+			$styleNode->parentNode->removeChild($styleNode);
+		}
+
+		return $css;
+	}
+
+	/**
+	 * Adds a style element with $css to $document.
+	 *
+	 * This method is protected to allow overriding.
+	 *
+	 * @see https://github.com/jjriv/emogrifier/issues/103
+	 *
+	 * @param \DOMDocument $document
+	 * @param string $css
+	 *
+	 * @return void
+	 */
+	protected function addStyleElementToDocument(DOMDocument $document, $css)
+	{
+		$styleElement = $document->createElement('style', $css);
+		$styleAttribute = $document->createAttribute('type');
+		$styleAttribute->value = 'text/css';
+		$styleElement->appendChild($styleAttribute);
+
+		$head = $this->getOrCreateHeadElement($document);
+		$head->appendChild($styleElement);
+	}
+
+	/**
+	 * Returns the existing or creates a new head element in $document.
+	 *
+	 * @param \DOMDocument $document
+	 *
+	 * @return \DOMNode the head element
+	 */
+	private function getOrCreateHeadElement(DOMDocument $document)
+	{
+		$head = $document->getElementsByTagName('head')->item(0);
+
+		if ($head === null) {
+			$head = $document->createElement('head');
+			$html = $document->getElementsByTagName('html')->item(0);
+			$html->insertBefore($head, $document->getElementsByTagName('body')->item(0));
+		}
+
+		return $head;
+	}
+
+	/**
+	 * Splits input CSS code to an array where:
+	 *
+	 * - key "css" will be contains clean CSS code
+	 * - key "media" will be contains all valuable media queries
+	 *
+	 * Example:
+	 *
+	 * The CSS code
+	 *
+	 *   "@import "file.css"; h1 { color:red; } @media { h1 {}} @media tv { h1 {}}"
+	 *
+	 * will be parsed into the following array:
+	 *
+	 *   "css" => "h1 { color:red; }"
+	 *   "media" => "@media { h1 {}}"
+	 *
+	 * @param string $css
+	 *
+	 * @return string[]
+	 */
+	private function splitCssAndMediaQuery($css)
+	{
+		$cssWithoutComments = preg_replace('/\\/\\*.*\\*\\//sU', '', $css);
+
+		$mediaTypesExpression = '';
+		if (!empty($this->allowedMediaTypes)) {
+			$mediaTypesExpression = '|' . implode('|', array_keys($this->allowedMediaTypes));
+		}
+
+		$cssForAllowedMediaTypes = preg_replace_callback(
+			'#@media\\s+(?:only\\s)?(?:[\\s{\\(]' . $mediaTypesExpression . ')\\s?[^{]+{.*}\\s*}\\s*#misU',
+			array( $this, '_media_concat' ),
+			$cssWithoutComments
+		);
+
+		// filter the CSS
+		$search = array(
+			'import directives' => '/^\\s*@import\\s[^;]+;/misU',
+			'remaining media enclosures' => '/^\\s*@media\\s[^{]+{(.*)}\\s*}\\s/misU',
+		);
+
+		$cleanedCss = preg_replace($search, '', $cssForAllowedMediaTypes);
+
+		return array('css' => $cleanedCss, 'media' => self::$_media);
+	}
+
+	private function _media_concat( $matches ) {
+		self::$_media .= $matches[0];
+	}
+
+	/**
+	 * Creates a DOMDocument instance with the current HTML.
+	 *
+	 * @return \DOMDocument
+	 */
+	private function createXmlDocument()
+	{
+		$xmlDocument = new DOMDocument;
+		$xmlDocument->encoding = 'UTF-8';
+		$xmlDocument->strictErrorChecking = false;
+		$xmlDocument->formatOutput = true;
+		$libXmlState = libxml_use_internal_errors(true);
+		$xmlDocument->loadHTML($this->getUnifiedHtml());
+		libxml_clear_errors();
+		libxml_use_internal_errors($libXmlState);
+		$xmlDocument->normalizeDocument();
+
+		return $xmlDocument;
+	}
+
+	/**
+	 * Returns the HTML with the unprocessable HTML tags removed and
+	 * with added document type and Content-Type meta tag if needed.
+	 *
+	 * @return string the unified HTML
+	 *
+	 * @throws \BadMethodCallException
+	 */
+	private function getUnifiedHtml()
+	{
+		$htmlWithoutUnprocessableTags = $this->removeUnprocessableTags($this->html);
+		$htmlWithDocumentType = $this->ensureDocumentType($htmlWithoutUnprocessableTags);
+
+		return $this->addContentTypeMetaTag($htmlWithDocumentType);
+	}
+
+	/**
+	 * Removes the unprocessable tags from $html (if this feature is enabled).
+	 *
+	 * @param string $html
+	 *
+	 * @return string the reworked HTML with the unprocessable tags removed
+	 */
+	private function removeUnprocessableTags($html)
+	{
+		if (empty($this->unprocessableHtmlTags)) {
+			return $html;
+		}
+
+		$unprocessableHtmlTags = implode('|', $this->unprocessableHtmlTags);
+
+		return preg_replace(
+			'/<\\/?(' . $unprocessableHtmlTags . ')[^>]*>/i',
+			'',
+			$html
+		);
+	}
+
+	/**
+	 * Makes sure that the passed HTML has a document type.
+	 *
+	 * @param string $html
+	 *
+	 * @return string HTML with document type
+	 */
+	private function ensureDocumentType($html)
+	{
+		$hasDocumentType = stripos($html, '<!DOCTYPE') !== false;
+		if ($hasDocumentType) {
+			return $html;
+		}
+
+		return self::DEFAULT_DOCUMENT_TYPE . $html;
+	}
+
+	/**
+	 * Adds a Content-Type meta tag for the charset.
+	 *
+	 * @param string $html
+	 *
+	 * @return string the HTML with the meta tag added
+	 */
+	private function addContentTypeMetaTag($html)
+	{
+		$hasContentTypeMetaTag = stristr($html, 'Content-Type') !== false;
+		if ($hasContentTypeMetaTag) {
+			return $html;
+		}
+
+		// We are trying to insert the meta tag to the right spot in the DOM.
+		// If we just prepended it to the HTML, we would lose attributes set to the HTML tag.
+		$hasHeadTag = stripos($html, '<head') !== false;
+		$hasHtmlTag = stripos($html, '<html') !== false;
+
+		if ($hasHeadTag) {
+			$reworkedHtml = preg_replace('/<head(.*?)>/i', '<head$1>' . self::CONTENT_TYPE_META_TAG, $html);
+		} elseif ($hasHtmlTag) {
+			$reworkedHtml = preg_replace(
+				'/<html(.*?)>/i',
+				'<html$1><head>' . self::CONTENT_TYPE_META_TAG . '</head>',
+				$html
+			);
+		} else {
+			$reworkedHtml = self::CONTENT_TYPE_META_TAG . $html;
+		}
+
+		return $reworkedHtml;
+	}
+
+	/**
+	 * @param string[] $a
+	 * @param string[] $b
+	 *
+	 * @return int
+	 */
+	private function sortBySelectorPrecedence(array $a, array $b)
+	{
+		$precedenceA = $this->getCssSelectorPrecedence($a['selector']);
+		$precedenceB = $this->getCssSelectorPrecedence($b['selector']);
+
+		// We want these sorted in ascending order so selectors with lesser precedence get processed first and
+		// selectors with greater precedence get sorted last.
+		$precedenceForEquals = ($a['line'] < $b['line'] ? -1 : 1);
+		$precedenceForNotEquals = ($precedenceA < $precedenceB ? -1 : 1);
+		return ($precedenceA === $precedenceB) ? $precedenceForEquals : $precedenceForNotEquals;
+	}
+
+	/**
+	 * @param string $selector
+	 *
+	 * @return int
+	 */
+	private function getCssSelectorPrecedence($selector)
+	{
+		$selectorKey = md5($selector);
+		if (!isset($this->caches[self::CACHE_KEY_SELECTOR][$selectorKey])) {
+			$precedence = 0;
+			$value = 100;
+			// ids: worth 100, classes: worth 10, elements: worth 1
+			$search = array('\\#','\\.','');
+
+			foreach ($search as $s) {
+				if (trim($selector) === '') {
+					break;
+				}
+				$number = 0;
+				$selector = preg_replace('/' . $s . '\\w+/', '', $selector, -1, $number);
+				$precedence += ($value * $number);
+				$value /= 10;
+			}
+			$this->caches[self::CACHE_KEY_SELECTOR][$selectorKey] = $precedence;
+		}
+
+		return $this->caches[self::CACHE_KEY_SELECTOR][$selectorKey];
+	}
+
+	private function translateCssToXpath_callback( $matches ) {
+		return strtolower($matches[0]);
+	}
+
+	/**
+	 * Maps a CSS selector to an XPath query string.
+	 *
+	 * @see http://plasmasturm.org/log/444/
+	 *
+	 * @param string $cssSelector a CSS selector
+	 *
+	 * @return string the corresponding XPath selector
+	 */
+	private function translateCssToXpath($cssSelector)
+	{
+		$paddedSelector = ' ' . $cssSelector . ' ';
+		$lowercasePaddedSelector = preg_replace_callback(
+			'/\\s+\\w+\\s+/',
+			array( $this, 'translateCssToXpath_callback' ),
+			$paddedSelector
+		);
+
+		$trimmedLowercaseSelector = trim($lowercasePaddedSelector);
+		$xPathKey = md5($trimmedLowercaseSelector);
+		if (!isset($this->caches[self::CACHE_KEY_XPATH][$xPathKey])) {
+			$roughXpath = '//' . preg_replace(
+					array_keys($this->xPathRules),
+					$this->xPathRules,
+					$trimmedLowercaseSelector
+				);
+			$xPathWithIdAttributeMatchers = preg_replace_callback(
+				self::ID_ATTRIBUTE_MATCHER,
+				array($this, 'matchIdAttributes'),
+				$roughXpath
+			);
+			$xPathWithIdAttributeAndClassMatchers = preg_replace_callback(
+				self::CLASS_ATTRIBUTE_MATCHER,
+				array($this, 'matchClassAttributes'),
+				$xPathWithIdAttributeMatchers
+			);
+
+			// Advanced selectors are going to require a bit more advanced emogrification.
+			// When we required PHP 5.3, we could do this with closures.
+			$xPathWithIdAttributeAndClassMatchers = preg_replace_callback(
+				'/([^\\/]+):nth-child\\(\\s*(odd|even|[+\\-]?\\d|[+\\-]?\\d?n(\\s*[+\\-]\\s*\\d)?)\\s*\\)/i',
+				array($this, 'translateNthChild'),
+				$xPathWithIdAttributeAndClassMatchers
+			);
+			$finalXpath = preg_replace_callback(
+				'/([^\\/]+):nth-of-type\\(\s*(odd|even|[+\\-]?\\d|[+\\-]?\\d?n(\\s*[+\\-]\\s*\\d)?)\\s*\\)/i',
+				array($this, 'translateNthOfType'),
+				$xPathWithIdAttributeAndClassMatchers
+			);
+
+			$this->caches[self::CACHE_KEY_SELECTOR][$xPathKey] = $finalXpath;
+		}
+		return $this->caches[self::CACHE_KEY_SELECTOR][$xPathKey];
+	}
+
+	/**
+	 * @param string[] $match
+	 *
+	 * @return string
+	 */
+	private function matchIdAttributes(array $match)
+	{
+		return ($match[1] !== '' ? $match[1] : '*') . '[@id="' . $match[2] . '"]';
+	}
+
+	/**
+	 * @param string[] $match
+	 *
+	 * @return string
+	 */
+	private function matchClassAttributes(array $match)
+	{
+		return ($match[1] !== '' ? $match[1] : '*') . '[contains(concat(" ",@class," "),concat(" ","' .
+		       implode(
+			       '"," "))][contains(concat(" ",@class," "),concat(" ","',
+			       explode('.', substr($match[2], 1))
+		       ) . '"," "))]';
+	}
+
+	/**
+	 * @param string[] $match
+	 *
+	 * @return string
+	 */
+	private function translateNthChild(array $match)
+	{
+		$parseResult = $this->parseNth($match);
+
+		if (isset($parseResult[self::MULTIPLIER])) {
+			if ($parseResult[self::MULTIPLIER] < 0) {
+				$parseResult[self::MULTIPLIER] = abs($parseResult[self::MULTIPLIER]);
+				$xPathExpression = sprintf(
+					'*[(last() - position()) mod %u = %u]/self::%s',
+					$parseResult[self::MULTIPLIER],
+					$parseResult[self::INDEX],
+					$match[1]
+				);
+			} else {
+				$xPathExpression = sprintf(
+					'*[position() mod %u = %u]/self::%s',
+					$parseResult[self::MULTIPLIER],
+					$parseResult[self::INDEX],
+					$match[1]
+				);
+			}
+		} else {
+			$xPathExpression = sprintf('*[%u]/self::%s', $parseResult[self::INDEX], $match[1]);
+		}
+
+		return $xPathExpression;
+	}
+
+	/**
+	 * @param string[] $match
+	 *
+	 * @return string
+	 */
+	private function translateNthOfType(array $match)
+	{
+		$parseResult = $this->parseNth($match);
+
+		if (isset($parseResult[self::MULTIPLIER])) {
+			if ($parseResult[self::MULTIPLIER] < 0) {
+				$parseResult[self::MULTIPLIER] = abs($parseResult[self::MULTIPLIER]);
+				$xPathExpression = sprintf(
+					'%s[(last() - position()) mod %u = %u]',
+					$match[1],
+					$parseResult[self::MULTIPLIER],
+					$parseResult[self::INDEX]
+				);
+			} else {
+				$xPathExpression = sprintf(
+					'%s[position() mod %u = %u]',
+					$match[1],
+					$parseResult[self::MULTIPLIER],
+					$parseResult[self::INDEX]
+				);
+			}
+		} else {
+			$xPathExpression = sprintf('%s[%u]', $match[1], $parseResult[self::INDEX]);
+		}
+
+		return $xPathExpression;
+	}
+
+	/**
+	 * @param string[] $match
+	 *
+	 * @return int[]
+	 */
+	private function parseNth(array $match)
+	{
+		if (in_array(strtolower($match[2]), array('even', 'odd'), true)) {
+			// we have "even" or "odd"
+			$index = strtolower($match[2]) === 'even' ? 0 : 1;
+			return array(self::MULTIPLIER => 2, self::INDEX => $index);
+		}
+		if (stripos($match[2], 'n') === false) {
+			// if there is a multiplier
+			$index = (int) str_replace(' ', '', $match[2]);
+			return array(self::INDEX => $index);
+		}
+
+		if (isset($match[3])) {
+			$multipleTerm = str_replace($match[3], '', $match[2]);
+			$index = (int) str_replace(' ', '', $match[3]);
+		} else {
+			$multipleTerm = $match[2];
+			$index = 0;
+		}
+
+		$multiplier = str_ireplace('n', '', $multipleTerm);
+
+		if ($multiplier === '') {
+			$multiplier = 1;
+		} elseif ($multiplier === '0') {
+			return array(self::INDEX => $index);
+		} else {
+			$multiplier = (int) $multiplier;
+		}
+
+		while ($index < 0) {
+			$index += abs($multiplier);
+		}
+
+		return array(self::MULTIPLIER => $multiplier, self::INDEX => $index);
+	}
+
+	/**
+	 * Parses a CSS declaration block into property name/value pairs.
+	 *
+	 * Example:
+	 *
+	 * The declaration block
+	 *
+	 *   "color: #000; font-weight: bold;"
+	 *
+	 * will be parsed into the following array:
+	 *
+	 *   "color" => "#000"
+	 *   "font-weight" => "bold"
+	 *
+	 * @param string $cssDeclarationsBlock the CSS declarations block without the curly braces, may be empty
+	 *
+	 * @return string[]
+	 *         the CSS declarations with the property names as array keys and the property values as array values
+	 */
+	private function parseCssDeclarationsBlock($cssDeclarationsBlock)
+	{
+		if (isset($this->caches[self::CACHE_KEY_CSS_DECLARATIONS_BLOCK][$cssDeclarationsBlock])) {
+			return $this->caches[self::CACHE_KEY_CSS_DECLARATIONS_BLOCK][$cssDeclarationsBlock];
+		}
+
+		$properties = array();
+		$declarations = preg_split('/;(?!base64|charset)/', $cssDeclarationsBlock);
+
+		foreach ($declarations as $declaration) {
+			$matches = array();
+			if (!preg_match('/^([A-Za-z\\-]+)\\s*:\\s*(.+)$/', trim($declaration), $matches)) {
+				continue;
+			}
+
+			$propertyName = strtolower($matches[1]);
+			$propertyValue = $matches[2];
+			$properties[$propertyName] = $propertyValue;
+		}
+		$this->caches[self::CACHE_KEY_CSS_DECLARATIONS_BLOCK][$cssDeclarationsBlock] = $properties;
+
+		return $properties;
+	}
+
+	/**
+	 * Find the nodes that are not to be emogrified.
+	 *
+	 * @param \DOMXPath $xPath
+	 *
+	 * @return \DOMElement[]
+	 */
+	private function getNodesToExclude(DOMXPath $xPath)
+	{
+		$excludedNodes = array();
+		foreach (array_keys($this->excludedSelectors) as $selectorToExclude) {
+			foreach ($xPath->query($this->translateCssToXpath($selectorToExclude)) as $node) {
+				$excludedNodes[] = $node;
+			}
+		}
+
+		return $excludedNodes;
+	}
+
+	/**
+	 * Handles invalid xPath expression warnings, generated by process() method,
+	 * during querying \DOMDocument and trigger \InvalidArgumentException
+	 * with invalid selector.
+	 *
+	 * @param int $type
+	 * @param string $message
+	 * @param string $file
+	 * @param int $line
+	 * @param array $context
+	 *
+	 * @return bool always false
+	 *
+	 * @throws \InvalidArgumentException
+	 */
+	public function handleXpathError($type, $message, $file, $line, array $context)
+	{
+		if ($type === E_WARNING && isset($context['cssRule']['selector'])) {
+			throw new InvalidArgumentException(
+				sprintf(
+					'%s in selector >> %s << in %s on line %s',
+					$message,
+					$context['cssRule']['selector'],
+					$file,
+					$line
+				)
+			);
+		}
+
+		// the normal error handling continues when handler return false
+		return false;
+	}
+}
diff --git a/templates/emails/email-styles.php b/templates/emails/email-styles.php
new file mode 100644
index 000000000..f885c6f9d
--- /dev/null
+++ b/templates/emails/email-styles.php
@@ -0,0 +1,38 @@
+<?php
+/**
+ * Email stylesheet.
+ *
+ * This template can be overridden by copying it to yourtheme/job_manager/emails/email-styles.php.
+ *
+ * @see         https://wpjobmanager.com/document/template-overrides/
+ * @author      Automattic
+ * @package     WP Job Manager
+ * @category    Template
+ * @version     1.31.0
+ */
+
+if ( ! defined( 'ABSPATH' ) ) {
+	exit; // Exit if accessed directly
+}
+
+$color_bg       = apply_filters( 'job_manager_email_style_background_color', '#fff');
+$color_fg       = apply_filters( 'job_manager_email_style_foreground_color', '#000');
+$color_link     = apply_filters( 'job_manager_email_style_link_color', '#036fa9');
+$font_family    = apply_filters( 'job_manager_email_style_font_family', '"Helvetica Neue", Helvetica, Roboto, Arial, sans-serif' );
+?>
+
+#wrapper {
+	background-color: <?php echo esc_attr( $color_bg ); ?>;
+	color: <?php echo esc_attr( $color_fg ); ?>;
+	margin: 0;
+	padding: 70px 0 70px 0;
+	-webkit-text-size-adjust: none !important;
+	width: 100%;
+	font-family: <?php echo esc_attr( $font_family ); ?>;
+}
+
+a {
+	color: <?php echo esc_attr( $color_link ); ?>;
+	font-weight: normal;
+	text-decoration: underline;
+}

From 69c655ea7fc6543cf7dc5a8bcb4c649d45825c07 Mon Sep 17 00:00:00 2001
From: Jake Oehler Morrison <jake.morrison@automattic.com>
Date: Wed, 11 Apr 2018 17:18:58 +0100
Subject: [PATCH 2/3] Adds email header and footer content handling

---
 ...ass-wp-job-manager-email-notifications.php | 32 ++++++++++++++++
 templates/emails/email-footer.php             | 30 +++++++++++++++
 templates/emails/email-header.php             | 37 +++++++++++++++++++
 templates/emails/plain/email-footer.php       | 17 +++++++++
 templates/emails/plain/email-header.php       | 17 +++++++++
 5 files changed, 133 insertions(+)
 create mode 100644 templates/emails/email-footer.php
 create mode 100644 templates/emails/email-header.php
 create mode 100644 templates/emails/plain/email-footer.php
 create mode 100644 templates/emails/plain/email-header.php

diff --git a/includes/class-wp-job-manager-email-notifications.php b/includes/class-wp-job-manager-email-notifications.php
index 738db322e..5a6eca97c 100644
--- a/includes/class-wp-job-manager-email-notifications.php
+++ b/includes/class-wp-job-manager-email-notifications.php
@@ -29,6 +29,8 @@ final class WP_Job_Manager_Email_Notifications {
 	public static function init() {
 		add_action( 'job_manager_send_notification', array( __CLASS__, '_schedule_notification' ), 10, 2 );
 		add_action( 'job_manager_email_init', array( __CLASS__, '_lazy_init' ) );
+		add_action( 'job_manager_email_header', array( __CLASS__, 'output_header' ), 10, 3 );
+		add_action( 'job_manager_email_footer', array( __CLASS__, 'output_footer' ), 10, 3 );
 	}
 
 	/**
@@ -176,6 +178,36 @@ public static function get_template_file_name( $template_name, $plain_text = fal
 		return implode( '/', $file_name_parts );
 	}
 
+	/**
+	 * Output email header.
+	 *
+	 * @param WP_Job_Manager_Email $email          Email object for the notification.
+	 * @param bool                 $sent_to_admin  True if this is being sent to an administrator.
+	 * @param bool                 $plain_text     True if the email is being sent as plain text.
+	 */
+	static public function output_header( $email, $sent_to_admin, $plain_text = false ) {
+		$template_segment = locate_job_manager_template( self::get_template_file_name( 'email-header', $plain_text ) );
+		if ( ! file_exists( $template_segment ) ) {
+			return;
+		}
+		include $template_segment;
+	}
+
+	/**
+	 * Output email footer.
+	 *
+	 * @param WP_Job_Manager_Email $email          Email object for the notification.
+	 * @param bool                 $sent_to_admin  True if this is being sent to an administrator.
+	 * @param bool                 $plain_text     True if the email is being sent as plain text.
+	 */
+	static public function output_footer( $email, $sent_to_admin, $plain_text = false ) {
+		$template_segment = locate_job_manager_template( self::get_template_file_name( 'email-footer', $plain_text ) );
+		if ( ! file_exists( $template_segment ) ) {
+			return;
+		}
+		include $template_segment;
+	}
+
 	/**
 	 * Returns the total number of deferred notifications to be sent. Used in unit tests.
 	 *
diff --git a/templates/emails/email-footer.php b/templates/emails/email-footer.php
new file mode 100644
index 000000000..197a2619e
--- /dev/null
+++ b/templates/emails/email-footer.php
@@ -0,0 +1,30 @@
+<?php
+/**
+ * Footer for email notifications.
+ *
+ * This template can be overridden by copying it to yourtheme/job_manager/emails/email-footer.php.
+ *
+ * @see         https://wpjobmanager.com/document/template-overrides/
+ * @author      Automattic
+ * @package     WP Job Manager
+ * @category    Template
+ * @version     1.31.0
+ */
+
+if ( ! defined( 'ABSPATH' ) ) {
+	exit; // Exit if accessed directly
+}
+?>
+										</div>
+									</td>
+								</tr>
+							</table>
+						</td>
+					</tr>
+				</table>
+			</td>
+		</tr>
+	</table>
+</div>
+</body>
+</html>
diff --git a/templates/emails/email-header.php b/templates/emails/email-header.php
new file mode 100644
index 000000000..4ab701114
--- /dev/null
+++ b/templates/emails/email-header.php
@@ -0,0 +1,37 @@
+<?php
+/**
+ * Header for email notifications.
+ *
+ * This template can be overridden by copying it to yourtheme/job_manager/emails/email-header.php.
+ *
+ * @see         https://wpjobmanager.com/document/template-overrides/
+ * @author      Automattic
+ * @package     WP Job Manager
+ * @category    Template
+ * @version     1.31.0
+ */
+
+if ( ! defined( 'ABSPATH' ) ) {
+	exit; // Exit if accessed directly
+}
+?>
+<!DOCTYPE html>
+<html <?php language_attributes(); ?>>
+<head>
+	<meta http-equiv="Content-Type" content="text/html; charset=<?php bloginfo( 'charset' ); ?>" />
+	<title><?php echo get_bloginfo( 'name', 'display' ); ?></title>
+</head>
+<body <?php echo is_rtl() ? 'rightmargin' : 'leftmargin'; ?>="0" marginwidth="0" topmargin="0" marginheight="0" offset="0">
+<div id="wrapper" dir="<?php echo is_rtl() ? 'rtl' : 'ltr'?>">
+	<table border="0" cellpadding="0" cellspacing="0" height="100%" width="100%">
+		<tr>
+			<td align="center" valign="top">
+				<!-- Body -->
+				<table border="0" cellpadding="0" cellspacing="0" width="600" id="template_body">
+					<tr>
+						<td valign="top" id="body_content">
+							<!-- Content -->
+							<table border="0" cellpadding="20" cellspacing="0" width="100%">
+								<tr>
+									<td valign="top">
+										<div id="body_content_inner">
diff --git a/templates/emails/plain/email-footer.php b/templates/emails/plain/email-footer.php
new file mode 100644
index 000000000..c1349e761
--- /dev/null
+++ b/templates/emails/plain/email-footer.php
@@ -0,0 +1,17 @@
+<?php
+/**
+ * Footer for email notifications.
+ *
+ * This template can be overridden by copying it to yourtheme/job_manager/emails/plain/email-footer.php.
+ *
+ * @see         https://wpjobmanager.com/document/template-overrides/
+ * @author      Automattic
+ * @package     WP Job Manager
+ * @category    Template
+ * @version     1.31.0
+ */
+
+if ( ! defined( 'ABSPATH' ) ) {
+	exit; // Exit if accessed directly
+}
+?>
diff --git a/templates/emails/plain/email-header.php b/templates/emails/plain/email-header.php
new file mode 100644
index 000000000..c1d84930b
--- /dev/null
+++ b/templates/emails/plain/email-header.php
@@ -0,0 +1,17 @@
+<?php
+/**
+ * Header for email notifications.
+ *
+ * This template can be overridden by copying it to yourtheme/job_manager/emails/plain/email-header.php.
+ *
+ * @see         https://wpjobmanager.com/document/template-overrides/
+ * @author      Automattic
+ * @package     WP Job Manager
+ * @category    Template
+ * @version     1.31.0
+ */
+
+if ( ! defined( 'ABSPATH' ) ) {
+	exit; // Exit if accessed directly
+}
+?>

From f01a8bbad7d71a1a3184a6dfdd0f2db15deee57c Mon Sep 17 00:00:00 2001
From: Jake Oehler Morrison <jake.morrison@automattic.com>
Date: Wed, 11 Apr 2018 17:32:27 +0100
Subject: [PATCH 3/3] Add basic tests for header and footer output

---
 ...ass.wp-job-manager-email-notifications.php | 30 ++++++++++++++++++-
 1 file changed, 29 insertions(+), 1 deletion(-)

diff --git a/tests/php/tests/includes/test_class.wp-job-manager-email-notifications.php b/tests/php/tests/includes/test_class.wp-job-manager-email-notifications.php
index f0ca53a67..81d676541 100644
--- a/tests/php/tests/includes/test_class.wp-job-manager-email-notifications.php
+++ b/tests/php/tests/includes/test_class.wp-job-manager-email-notifications.php
@@ -80,7 +80,7 @@ public function test_send_deferred_notifications_valid_email() {
 		$this->assertEmpty( $sent_email->cc );
 		$this->assertEmpty( $sent_email->bcc );
 		$this->assertEquals( 'Test Subject', $sent_email->subject );
-		$this->assertEquals( "<p><strong>test</strong></p>\n", $sent_email->body );
+		$this->assertContains( "<p><strong>test</strong></p>\n", $sent_email->body );
 		$this->assertContains( 'From: From Name <from@example.com>', $sent_email->header );
 		$this->assertContains( 'Content-Type: text/html;', $sent_email->header );
 	}
@@ -188,6 +188,34 @@ public function test_get_template_file_name_rich() {
 		$this->assertEquals( "emails/{$template_name}.php", WP_Job_Manager_Email_Notifications::get_template_file_name( $template_name, false ) );
 	}
 
+	/**
+	 * @covers WP_Job_Manager_Email_Notifications::output_header()
+	 */
+	public function test_output_header() {
+		add_filter( 'job_manager_email_notifications', array( $this, 'inject_email_config_valid_email' ) );
+		$emails = WP_Job_Manager_Email_Notifications::get_email_notifications( false );
+		remove_filter( 'job_manager_email_notifications', array( $this, 'inject_email_config_valid_email' ) );
+		$email = $emails['valid-email'];
+		ob_start();
+		WP_Job_Manager_Email_Notifications::output_header( $email, true, false );
+		$content = ob_get_clean();
+		$this->assertContains( '<!DOCTYPE html>', $content );
+	}
+
+	/**
+	 * @covers WP_Job_Manager_Email_Notifications::output_footer()
+	 */
+	public function test_output_footer() {
+		add_filter( 'job_manager_email_notifications', array( $this, 'inject_email_config_valid_email' ) );
+		$emails = WP_Job_Manager_Email_Notifications::get_email_notifications( false );
+		remove_filter( 'job_manager_email_notifications', array( $this, 'inject_email_config_valid_email' ) );
+		$email = $emails['valid-email'];
+		ob_start();
+		WP_Job_Manager_Email_Notifications::output_footer( $email, true, false );
+		$content = ob_get_clean();
+		$this->assertContains( '</html>', $content );
+	}
+
 	/**
 	 * Helper Methods
 	 */