diff --git a/lib/cssp.php b/lib/cssp.php
index 4c18599..094a669 100644
--- a/lib/cssp.php
+++ b/lib/cssp.php
@@ -384,7 +384,7 @@ private function apply_copying_values($block, $selector, $property, $values, $fo
 				preg_match_all($copying_pattern, $values[$i], $matches);
 				// Exact selector matches
 				if(isset($this->parsed[$block][$matches[1][0]][$matches[2][0]])){
-					$dest[$i] = $this->get_final_value($this->parsed[$block][$matches[1][0]][$matches[2][0]], $property);
+					$dest[$i] = str_replace($matches[0][0], $this->get_final_value($this->parsed[$block][$matches[1][0]][$matches[2][0]], $property), $dest[$i]);
 					$found = true;
 				}
 				// Search for partial selector matches, ie. "#foo" in "#bar, #foo, #blah"
@@ -393,7 +393,7 @@ private function apply_copying_values($block, $selector, $property, $values, $fo
 						$tokenized_selectors = $this->tokenize($full_selectors, ',');
 						if(in_array($matches[1][0], $tokenized_selectors)){
 							if(isset($this->parsed[$block][$full_selectors][$matches[2][0]])){
-								$dest[$i] = $this->get_final_value($this->parsed[$block][$full_selectors][$matches[2][0]], $property);
+								$dest[$i] = str_replace($matches[0][0], $this->get_final_value($this->parsed[$block][$full_selectors][$matches[2][0]], $property), $dest[$i]);
 								$found = true;
 							}
 						}
diff --git a/plugins/math.php b/plugins/math.php
new file mode 100644
index 0000000..7fa1eac
--- /dev/null
+++ b/plugins/math.php
@@ -0,0 +1,142 @@
+<?php
+
+/**
+ * This file is part of Turbine
+ * http://github.com/SirPepe/Turbine
+ * 
+ * Copyright Peter Kröner
+ * Licensed under GNU LGPL 3, see license.txt or http://www.gnu.org/licenses/
+ */
+ 
+ /**
+ * Math plugin created by Raymond Geerts
+ * Calculates values of same unit
+ * 
+ * Usage:   Any property that can contain measurement units 
+ * 			will be able to calculate its final value from
+ * 			units of the same type.
+ * Example: width: 100px+150px
+ * Example: height: 15px / 3 * 2
+ * Example: margin: 2px+2px 1em+0.5em 2px+2px 1px+5px
+ * Example: padding: 6px+3px (-1px) 5px (-1px)
+ * Example: background-positon: 12px * 2 12px / 2
+ * Status:  Stable
+ * Version: 1.1
+ * 
+ * @param mixed &$parsed
+ * @return void
+ */
+ 
+function math(&$parsed){
+ 	global $cssp;
+ 	$units = array('%', 'in', 'cm', 'mm', 'em', 'ex', 'pt', 'pc', 'px');
+ 	
+ 	$unitspattern = '/('.implode("|", $units).')/i';
+	
+ 	$properties = array(
+ 		/* Background -> xpos ypos */
+		'background', 'background-position', 
+		/* Border -> length */
+		'border', 'border-width', 'border-bottom', 'border-bottom-width', 'border-left', 'border-left-width', 'border-right', 'border-right-width', 'border-top', 'border-top-width', 'border-spacing', 
+		/* Dimension -> length */
+		'height', 'line-height', 'max-height', 'min-height', 'width', 'max-width', 'min-width', 
+		/* Font -> length */
+		'font', 'font-size', 
+		/* List -> length */
+		'marker-offset', 
+		/* Margin -> length */
+		'margin', 'margin-bottom', 'margin-left', 'margin-right', 'margin-top', 
+		/* Outline -> length */
+		'outline', 'outline-width',
+		/* Padding -> length */
+		'padding', 'padding-bottom', 'padding-left', 'padding-right', 'padding-top',
+		/* Positioning -> length */
+		'bottom', 'left', 'right', 'top',
+		/* Text -> length */
+		'letter-spacing', 'text-indent', 'word-spacing'
+	 );
+	// For every possible property...
+	foreach($properties as $search){
+		// ... loop through the css...
+		foreach($parsed as $block => $css){
+			foreach($parsed[$block] as $selector => $styles){
+				if($selector != '@turbine' && isset($parsed[$block][$selector][$search])){
+					$num_values = count($parsed[$block][$selector][$search]);
+					// ... loop through the values
+					for($i = 0; $i < $num_values; $i++){
+						// generate empty array
+						$occurences = array();
+						if(preg_match('/[\s]*[*\/+-][\s]*/',$parsed[$block][$selector][$search][$i])){
+							// remove spaces inbetween values to calculate
+							$parsed[$block][$selector][$search][$i] = preg_replace('/[\s]*([*\/+-])[\s]*/','$1',$parsed[$block][$selector][$search][$i]);
+							// put each part with its own key in an array
+							$occurences = preg_split('/[\s]+/',$parsed[$block][$selector][$search][$i]);
+							// generate empty array's
+							$unit = array();
+							$unitcheck = array();
+							foreach($occurences AS $key=>$occurence){
+								$count = 0;
+								if (preg_match_all($unitspattern, $occurence, $matches, PREG_PATTERN_ORDER)){
+									$count = count(array_unique($matches[0]));
+									$unitcheck[$key] = $count;
+									$unit[$key] = ($count<2)?$matches[0][0]:null;
+								}
+								else
+								{
+									$unitcheck[$key] = '0';
+									$unit[$key] = null;
+								}
+							}
+							$comment = null;
+							$output = array();
+							foreach($occurences AS $key=>$occurence){
+								if ($unitcheck[$key]==0) {
+									$output[$key] = $occurence;
+								}
+								else if ($unitcheck[$key]==1) {
+									$occurence = preg_replace($unitspattern,'',$occurence);
+									$occurence = preg_replace('/[$a-zA-Z_]/','',$occurence);
+									$output[$key] = @eval("return (" . $occurence . ");").$unit[$key];
+								}
+								else {
+									$output[$key] = $occurence;
+									$unique = array();
+									foreach($unit AS $u) {
+										if($u) $unique[] = $u;
+									}
+									$comment = 'math plugin: incompatible units '.implode(', ', array_unique($unique));
+								}
+							}
+						
+							$cssp->parsed[$block][$selector][$search][0] = implode(' ', $output);
+							
+							if(!$comment){
+								CSSP::comment(
+									$cssp->parsed[$block][$selector], 
+									$search, 
+									'math plugin: calcutated value'
+								);
+							}
+							else {
+								CSSP::comment(
+									$cssp->parsed[$block][$selector], 
+									$search, 
+									$comment
+								);
+							}
+						}
+					}
+				}
+			}
+		}
+	}
+}
+
+
+/**
+ * Register the plugin
+ */
+$cssp->register_plugin('before_glue', 0, 'math');
+
+
+?>
\ No newline at end of file