我可以看到这可能与 css 的唯一方法是以某种方式使用 :not 选择器，但我无法弄清楚。下面的注释说明了鼠标悬停时应该处于活动状态的悬停状态。
<div class='node'> // node is activated
<div class='node'></div> // node is activated but parent is de-activated
<div class='node'> // node and children are activated but parent is de-activated
<div class='node'>
<div class='node'></div>
</div>
</div>
</div>
Plunkr：