Slider: fix slider positioning

packages/slider/src/button.vue

@@ -110,7 +110,7 @@
       onDragStart(event) {
         this.dragging = true;
         this.startX = event.clientX;
-        this.startPosition = parseInt(this.currentPosition, 10);
+        this.startPosition = parseFloat(this.currentPosition);
       },
 
       onDragging(event) {