fix

@@ -40,9 +40,10 @@ export default {
     },
     titleStyle() {
       let style = {};
+      let stepPercent = this.stepPercent;
 
       if (this.offsetLeft) {
-        style.transform = `translate3d(${-this.stepPercent * this.offsetLeft}px, 0, 0)`;
+        style.transform = `translate3d(${-stepPercent * this.offsetLeft}px, 0, 0)`;
       } else {
         this.updateTitleOffset();
       }