Grammatical fix.

Author: rebeccacremona

1-js/02-first-steps/18-javascript-specials/article.md

@@ -55,7 +55,7 @@ To fully enable all features of modern JavaScript, we should start scripts with
 
 The directive must be at the top of a script or at the beginning of a function body.
 
-Without `"use strict"`, everything still works, but some features behave in the old-fashion, "compatible" way. We'd generally prefer the modern behavior.
+Without `"use strict"`, everything still works, but some features behave in the old-fashioned, "compatible" way. We'd generally prefer the modern behavior.
 
 Some modern features of the language (like classes that we'll study in the future) enable strict mode implicitly.