diff --git a/format-master.xml b/format-master.xml
index 857b2e3..37d8804 100755
--- a/format-master.xml
+++ b/format-master.xml
@@ -1812,19 +1812,19 @@
 					<xsl:value-of select="@border" />
 					<xsl:if test="not(@border)">0</xsl:if>
 				</xsl:attribute>
-				<xsl:choose>
-					<xsl:when test="@align='center'">
-						<xsl:attribute name="style">
-							<xsl:text>margin-left:auto; margin-right: auto;</xsl:text>
-						</xsl:attribute>
-					</xsl:when>
-					<xsl:when test="@align='right'">
-						<xsl:attribute name="style">
-							<xsl:text>margin-left:auto;</xsl:text>
-						</xsl:attribute>
-					</xsl:when>
-					<xsl:otherwise />
-				</xsl:choose>
+				<xsl:attribute name="cellspacing">0</xsl:attribute>
+				<xsl:attribute name="style">
+					<xsl:text>border-collapse: collapse; </xsl:text>
+					<xsl:choose>
+						<xsl:when test="@align='center'">
+							<xsl:text>margin-left:auto; margin-right: auto; </xsl:text>
+						</xsl:when>
+						<xsl:when test="@align='right'">
+							<xsl:text>margin-left:auto; </xsl:text>
+						</xsl:when>
+						<xsl:otherwise />
+					</xsl:choose>
+				</xsl:attribute>
 				<!--
 					Note different ordering of tabular components:
 					HTML requires THEAD and TFOOT to precede TBODY.
@@ -1927,13 +1927,93 @@
 		@columns: The column range to draw the rule across. Specify as
 		you would for a \cline in LaTeX, e.g., '3-5'. If omitted, the
 		rule is drawn across all columns.
+		
+		@weight: The weight of the rule. Note that double weight isn't
+		available for partial rules in LaTeX, because repeated \cline
+		macros simply draw over the top of each other.
+			'single' [default]
+			'double' = a double rule
 	-->
 	<template name="row-rule-full" match="row-rule[not(@columns)]">
-		<common formats="/latex/xelatex/"><xsl:text>\hline </xsl:text></common>
+		<common formats="/latex/xelatex/">
+			<xsl:text>\hline</xsl:text>
+			<xsl:if test="@weight = 'double'"><xsl:text>\hline</xsl:text></xsl:if>
+			<xsl:text> </xsl:text>
+		</common>
+		<common formats="/html/xhtml/">
+			<tr>
+				<td>
+					<xsl:attribute name="style">
+						<xsl:text>border-bottom: 1px solid black; </xsl:text>
+						<!--
+							This is a bit of a hack to get a double border,
+							as some browsers don't support the "double" border
+							style yet. It looks slightly ugly, but works.
+						-->
+						<xsl:if test="@weight = 'double'">
+							<xsl:text>border-top: 1px solid black; </xsl:text>
+						</xsl:if>
+					</xsl:attribute>
+					<xsl:attribute name="colspan">
+						<xsl:value-of select="count(ancestor::tabular/tabular-columns/column)" />
+					</xsl:attribute>
+				</td>
+			</tr>
+		</common>
 	</template>
 
 	<template name="row-rule-partial" match="row-rule[@columns]">
-		<common formats="/latex/xelatex/">\cline{<xsl:value-of select="@columns" />}</common>
+		<common formats="/latex/xelatex/">
+			<!-- Tokenise the column specifications for later reference. -->
+			<xsl:variable name="column-specs" select="tokenize(@columns, ',')" />
+			<xsl:for-each select="$column-specs">
+				<xsl:text>\cline{</xsl:text>
+				<xsl:value-of select="." />
+				<!-- Normalise the value to a range if necessary. -->
+				<xsl:if test="not(contains(., '-'))">
+					<xsl:text>-</xsl:text>
+					<xsl:value-of select="." />
+				</xsl:if>
+				<xsl:text>}</xsl:text>
+			</xsl:for-each>
+		</common>
+		<common formats="/html/xhtml/">
+			<!-- Tokenise the column specifications for later reference. -->
+			<xsl:variable name="column-specs" select="tokenize(@columns, '[-,]')" />
+			
+			<!--
+				We need to store the value of @weight, because the context will
+				be changed by the for-each loop below. Default to "single" in
+				any case.
+			-->
+			<xsl:variable name="weight">
+				<xsl:value-of select="@weight" />
+				<xsl:if test="not(@weight)">
+					<xsl:text>single</xsl:text>
+				</xsl:if>
+			</xsl:variable>
+			
+			<tr>
+				<!--
+					Loop through all of the columns in the table, testing to
+					see whether the column index exists in $column-specs. If
+					so, add a border to the cell. Note that this loop changes
+					the current context!
+				-->
+				<xsl:for-each select="1 to count(ancestor::tabular/tabular-columns/column)">
+					<td>
+						<xsl:if test="exists(index-of($column-specs, . cast as xs:string))">
+							<xsl:attribute name="style">
+								<xsl:text>border-bottom: 1px solid black; </xsl:text>
+								<xsl:if test="$weight = 'double'">
+									<xsl:text>border-top: 1px solid black; </xsl:text>
+								</xsl:if>
+							</xsl:attribute>
+						</xsl:if>
+					</td>
+				</xsl:for-each>
+			</tr>
+		</common>
 	</template>
 	
 	<!--