better-scroll

我按照better-scroll 文档写的demo,为什么不能滚动，以下是代码

<template>
    <div>
        <div class="wrapper" ref="wrapper">
            <div class="content">
                <div class="list" v-for="item in list">item</div>
            </div>            
        </div>
    </div>
</template>
<script>
import BScroll from 'better-scroll'
    export default{
        data(){
            return{
                list:[1,2,3,4,5,6,7,,8,9,1,2,3,4,,54,12,3,2]
            }
        },
        mounted(){
            this.$nextTick(() => {
                this.InitScroll()
              })
        },
        methods:{
            InitScroll(){
                new BScroll(this.$refs.wrapper, {
                    click:true,
                    scrollY:true,
                    startY:0
                })
            }
        }
    }
</script>
<style>
    .wrapper{
        height: 6rem;
        overflow: hidden;
    }
    .list{
        height: 2rem;
        line-height: 2rem;
        text-align: center;
    }
</style>

这是渲染后的图片，请问问题出在哪里？