CSSの経験

：番目の子（）セレクタ

nth-child(2)的意思是当前元素的父元素的第二个子元素

<div>
    <i>好</i>                         //i:nth-child(1)
    <i>好</i>                         //i:nth-child(2)
    <span>哈</span>           //span:nth-child(3)
    <span>哈</span>           //span:nth-child(4)
    <span>哈</span>           //span:nth-child(5)
    <i>好</i>                         //i:nth-child(6)
    <span>哈</span>           //span:nth-child(7)
</div>