fix: invisible BibTeX citation in dark mode

Regression from migration of HLJS to Hugo's Chroma.

Fix #2753

wowchemy/assets/scss/wowchemy/_dark.scss

@@ -48,6 +48,7 @@ body.dark,
 .dark pre {
   /* Match `pre` bg color. */
   border-color: rgb(68, 71, 90);
+  color: #fff;  // Override Bootstrap default (light mode only)
 }
 
 .dark mark,

wowchemy/layouts/partials/citation.html

@@ -9,7 +9,8 @@
         </button>
       </div>
       <div class="modal-body">
-        <pre><code class="tex hljs"></code></pre>
+        <!-- Citation is dynamically injected via JS -->
+        <pre><code></code></pre>
       </div>
       <div class="modal-footer">
         <a class="btn btn-outline-primary my-1 js-copy-cite" href="#" target="_blank">
@@ -22,4 +23,4 @@
       </div>
     </div>
   </div>
-</div>
+</div>