Fix inline code font size in headings (#2220)

Author: standard-librarian

assets/css/content/code.css

@@ -39,6 +39,10 @@
   word-wrap: break-word;
 }
 
+.content-inner :is(h1, h2, h3, h4, h5, h6) code {
+  font-size: 0.875em;
+}
+
 .content-inner pre {
   margin: var(--baseLineHeight) 0;
 }