ui-blame: Allow syntax highlighting

Place file contents into a single block so that syntax highlighting can
be applied in the usual fashion.  Place the alternating color bars
behind the file contents.  Force the default syntax highlighting
background to transparent.

Signed-off-by: Jeff Smith <whydoubt@gmail.com>
Reviewed-by: John Keeping <john@keeping.me.uk>
diff --git a/cgit.css b/cgit.css
index 20b7e86..217a05a 100644
--- a/cgit.css
+++ b/cgit.css
@@ -353,6 +353,16 @@
 	background: white;
 }
 
+div#cgit table.blame td.lines > div {
+	position: relative;
+}
+
+div#cgit table.blame td.lines > div > pre {
+	padding: 0 0 0 0.5em;
+	position: absolute;
+	top: 0;
+}
+
 div#cgit table.bin-blob {
 	margin-top: 0.5em;
 	border: solid 1px black;