1. 样式绑定
   <div v-show="visible" :style="customStyle" class="back-to-ceiling" @click="backToTop">
   customStyle: {
   type: Object,
   default: function() {
   return {
   right: '50px',
   bottom: '50px',
   width: '40px',
   height: '40px',
   'border-radius': '4px',
   'line-height': '45px',
   background: '#e7eaf1'
   }
   }
   },

2.Window pageXOffset 和 pageYOffset 属性
https://www.runoob.com/jsref/prop-win-pagexoffset.html
(基于vue-element-admin backToTop组件)

3.Sass之&引用父选择器
https://www.iteye.com/blog/lixh1986-2428306

4.flex布局的几点
justify-content: space-around;
align-items: flex-start;
flex-direction: row;

5.Vue 拖拽组件 vuedraggable 和 vue-dragging
http://www.ptbird.cn/vue-draggable-dragging.html