adding new handle for offset

package.json

@@ -1,6 +1,6 @@
 {
     "name": "tiny-one-page",
-    "version": "1.0.2",
+    "version": "1.0.3",
     "description": "One Page Menu with RiotJS, part of Tiny-Components",
     "scripts": {
         "dev": "npm run development",

src/TinyOnePage.riot

@@ -228,7 +228,13 @@
                 const elements = this.$$('.' + this.state.namespace + '__inner a');
 
                 // @TODO check offset
-                const offset = this.state.options.offset - 25;
+                let offset = 25;
+
+                if (typeof this.state.options.offset === "function") {
+                    offset = this.state.options.offset() - offset;
+                } else {
+                    offset = this.state.options.offset - offset;
+                }
 
                 // if found
                 let hasFound = false;
@@ -237,9 +243,9 @@
                 let result = undefined;
 
                 if (window.pageYOffset > offset) {
-                    document.querySelector('body').classList.add('is-scrolling');
+                    document.querySelector('body').classList.add('has-scrolled');
                 } else {
-                    document.querySelector('body').classList.remove('is-scrolling');
+                    document.querySelector('body').classList.remove('has-scrolled');
                 }
 
                 elements.forEach(function(element, index) {