box-sizing border-box
position relative
transition all .15s ease
width 16px
height 16px

&:before,
&:after
  border 1px solid
  border-color initial
  border-radius 6px
  box-sizing border-box
  content ""
  display block
  height 2px
  left 50%
  position absolute
  top 50%
  transform translate(-50%,-50%)
  transition all .15s ease
  width 100%

&:after
  width 2px
  height 100%