diff --git a/xsl/xhtml5.xsl b/xsl/xhtml5.xsl
index 19a98aa5e..7fca1aaa6 100644
--- a/xsl/xhtml5.xsl
+++ b/xsl/xhtml5.xsl
@@ -3,7 +3,8 @@
   xmlns="http://www.w3.org/1999/xhtml"
   xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
   xmlns:date="http://exslt.org/dates-and-times"
-  exclude-result-prefixes="xsl">
+  xmlns:crypto="http://exslt.org/crypto"
+  exclude-result-prefixes="xsl date crypto">
 
 
 <xsl:include href="common.xsl" />
@@ -358,10 +359,18 @@
 	  </xsl:attribute>
 	</xsl:if>
 	<xsl:if test="@class = 'wiki'">
+	  <xsl:variable name="number"
+			select="translate(
+				crypto:md5(content-text),
+				'abcdefABCDEF', '123456123456')"/>
 	  <xsl:attribute name="style">
-	    background-color: rgb(<xsl:value-of select="240 - 3 *
-	    string-length(content-text)"/>, <xsl:value-of select="252
-	    - 4 * string-length(content-text)"/>, 255);
+	    <xsl:text>background-color: rgb(</xsl:text>
+	    <xsl:value-of select="255 - number(substring($number, 1, 2))"/>
+	    <xsl:text>, </xsl:text>
+	    <xsl:value-of select="255 - number(substring($number, 3, 2))"/>
+	    <xsl:text>, </xsl:text>
+	    <xsl:value-of select="255 - number(substring($number, 5, 2))"/>
+	    <xsl:text>);</xsl:text>
 	  </xsl:attribute>
 	</xsl:if>