fix(style): code font-family no longer loaded from font theme

$sta-font-mono was referenced as literal during CSS->SCSS conversion.

Fix #1139

assets/sass/academic/_root.scss

@@ -159,7 +159,7 @@ figcaption h4 {
 
 pre,
 code {
-  font-family: '$sta-font-mono', monospace;
+  font-family: $sta-font-mono, monospace;
   color: #c7254e;
   background-color: #f9f2f4;
 }