Allow modification of the value of rem

scss/_reboot.scss

@@ -17,6 +17,14 @@
   box-sizing: border-box;
 }
 
+// Root
+//
+// 1. Ability to the value of the root font sizes, affecting the value of `rem`.
+//    null by default, thus nothing is generated.
+
+:root {
+  font-size: $font-size-root; // 1
+}
 
 // Body
 //