Revert "Point to primer-base and comment out marketing"

This reverts commit 724538d.

Author: lildude

assets/css/index.scss

@@ -1,8 +1,8 @@
 ---
 ---
 
-@import "primer-base/index.scss";
-//@import "primer-marketing/index.scss";
+@import "primer-core/index.scss";
+@import "primer-marketing/index.scss";
 @import "toc.scss";
 @import "custom.scss";
 @import "covers.scss";