fix: increase codeblock title contrast (#22713)

Author: ArthurFlag

layouts/_default/_markup/render-codeblock.html

@@ -1,6 +1,8 @@
 <div data-pagefind-ignore class="scroll-mt-2" x-data x-ref="root">
   {{ with .Attributes.title }}
-    <div class="mb-3 text-sm text-gray-100 dark:bg-gray-900 dark:text-gray-900">
+    <div
+      class="mb-0 rounded-sm bg-gray-100 p-2 text-sm text-gray-900 dark:bg-gray-900 dark:text-gray-200"
+    >
       {{ . }}
     </div>
   {{ end }}