Fix code block font for event loop diagram

Author: Herrtian

template.html

@@ -34,6 +34,12 @@
       rel="stylesheet"
       href="https://fonts.googleapis.com/css2?family=IBM+Plex+Mono&family=Open+Sans:ital,wght@0,300..800;1,300..800"
     />
+    <style>
+      main pre code {
+        font-family: var(--font-mono);
+        font-weight: var(--font-weight-regular);
+      }
+    </style>
 
     <!-- Apply theme before paint to avoid Flash of Unstyled Content -->
     <script>