docs: Fix CSS for dark mode code blocs (see #4085)

Author: magreenblatt

docs/assets/css/style.scss

@@ -67,15 +67,23 @@ a:hover {
     color: #f0f0f0;
   }
 
-  code, pre {
-    background-color: #2d2d2d;
-    color: #e0e0e0;
+  code {
+    background-color: #3a3a3a;
+    color: #e8e8e8;
+    border: 1px solid #555;
   }
 
   pre {
+    background-color: #2d2d2d;
     border: 1px solid #444;
   }
 
+  pre code {
+    background-color: transparent;
+    border: none;
+    color: #e0e0e0;
+  }
+
   blockquote {
     border-left-color: #555;
     color: #b0b0b0;