Update semantics

src/epub/css/local.css

@@ -6,7 +6,7 @@ footer{
 	text-align: right;
 }
 
-abbr.era{
+[epub|type~="se:era"]{
 	font-variant: all-small-caps;
 }
 

src/epub/text/chapter-15.xhtml

@@ -267,7 +267,7 @@
 			<p>Don Luis appeared to be delighted. He had an audience, a full bench of judges. Vorski was writhing on his tree. It was an exquisite moment.</p>
 			<p>He cut a sort of caper which must have reminded Vorski of the ancient Druid’s pirouettes and, drawing himself up, bowed, imitated a lecturer taking a sip of water from a tumbler, rested his hands on an imaginary table and at last began, in a deliberate voice:</p>
 			<p>“Ladies and Gentlemen:</p>
-			<p>“On the twenty-fifth of July, in the year seven hundred and thirty-two <abbr class="era">B.C.</abbr>⁠ ⁠…”</p>
+			<p>“On the twenty-fifth of July, in the year seven hundred and thirty-two <abbr epub:type="se:era">B.C.</abbr>⁠ ⁠…”</p>
 		</section>
 	</body>
 </html>