pointer-events: none

目的

讓元素可以被穿透

.box
 .back
 .front 
  |hover
  br
  |me

.box
 width: 300px
 height: 300px
 position: relative
 
.back
 background-color: teal
 width: 100px
 height: 100px
 &:hover
  background-color: darkgreen
 
 
.front
 background-color: skyblue
 width: 100px
 height: 100px
 position: absolute
 top: 0
 left: 50px
 opacity: 0.5
 pointer-events: none

Display