Synchronize chapter and navigation translations with Chinese prose indentation

src/assembly/bilingual_style.css

@@ -1,4 +1,4 @@
-/* Preserve the book's alignment, indent and inline font choices. */
+/* Preserve publisher alignment and inline fonts; apply Chinese prose indentation. */
 .translation {
     line-height: 1.6;
     clear: both;
@@ -17,3 +17,8 @@ p.translation::first-letter {
     color: inherit !important;
     float: none !important;
 }
+/* Prose gets two Chinese character widths, including chapter-opening prose.
+   Headings, captions, quotations and note markers keep their own layout. */
+.translation[data-translation-role="body"] {
+    text-indent: 2em !important;
+}