ids theme: reliably render "Authors (Year):" as bold first line in bibliography

The old CSS hack inserted a line break before the FIRST ELEMENT CHILD of
each .csl-entry, plus a ::first-line tint. Which part of an entry
citeproc wraps in spans anchors depends on the entry type, so the break
landed arbitrarily -- e.g. mid-title in the DeLiKo entry or before the
final URL. Replace it with an explicit wrap: the theme template walks
the leading text nodes of each entry to the first "):" and marks them
as .csl-authors-year (display: block; bold; mid blue-gray), which is
both the bold first line and the line break. Entries without a year
marker are left untouched; spacing between entries is restored with a
0.5em margin (pandoc's div.csl-entry pins it to 0em otherwise). The
demo bibliography gains the DeLiKo citation as a regression case.

Change-Id: I196368e631a8870d63fe2022fb5cda3a0ad30072
diff --git a/inst/reveal.js-5.1.0/dist/theme/ids.css b/inst/reveal.js-5.1.0/dist/theme/ids.css
index b8c44f3..da527dd 100644
--- a/inst/reveal.js-5.1.0/dist/theme/ids.css
+++ b/inst/reveal.js-5.1.0/dist/theme/ids.css
@@ -808,18 +808,21 @@
   text-indent: -22px;
 }
 
-.csl-entry::first-line {
-  color: #253b43;
-}
-
-.csl-entry {
+/* .references scopes this above pandoc's CSL defaults (div.csl-entry), which
+   otherwise win on specificity and pin margin-bottom to 0em. */
+.references .csl-entry {
   color: #888888;
+  margin-bottom: 0.5em;
 }
 
-/* Add line break after authors and year*/
-.csl-entry :first-child::before {
-  content: "\a";
-  white-space: pre;
+/* "Authors (Year):" as a bold dark first line; the theme template's JS wraps
+   the leading text of each entry in .csl-authors-year (see default.html) --
+   which part of an entry citeproc wraps in spans depends on the entry type, so
+   a CSS-only break cannot place it reliably. */
+.csl-entry .csl-authors-year {
+  display: block;
+  font-weight: bold;
+  color: #4d616b;
 }
 
 .reveal code.sourceCode:last-child+pre {