关于.spinner .line2的问题

Question

为什么对单个矩形设置animation-delay属性时要写成.spinner .line2{animation-delay: -1.1s;}而不能写成.line2{animation-delay: -1.1s;}p.s.html部分如下：<div class="spinner"> <div class="line1"></div> <div class="line2"></div> <div class="line3"></div> <div class="line4"></div> <div class="line5"></div></div>

Answer 1

1. 层级比较清晰

2. 加强了权重