Adds missing semi-colon

Author: Professor Bitner

_sass/_syntax.scss

@@ -10,7 +10,7 @@ div.highlighter-rouge, figure.highlight {
   border-radius: $border-radius;
   background-color: $code-background-color;
   box-shadow: $box-shadow;
-  font-size: $type-size-4
+  font-size: $type-size-4;
 
   &:before {
     position: absolute;