Add styles to Less

public/less/_form.less

@@ -80,6 +80,16 @@
         }
     }
 }
+.signup {
+    @media only screen and (min-width: 768px) {
+        .g-recaptcha {
+            margin: 0 auto;
+            width: 304px;
+            padding-left: 30px;
+        }	
+    }
+}
+
 .user.activate,
 .user.forgot.password,
 .user.reset.password,