//代码块复制按钮
.highlight
  //方便copy代码按钮（btn-copy）的定位
  position: relative

.btn-copy
  z-index: 1
  display: inline-block
  cursor: pointer
  border: none
  disable-user-select()
  -webkit-appearance: none
  font-family: Menlo, $fontfamily-code
  font-size: 11px
  font-weight: bold
  padding: $gap * 0.25 $gap * 0.5
  >i
    margin-right: 4px
  color: var(--color-meta)
  background: var(--color-block)
  border-radius: 3px
  box-shadow: $boxshadow-card
  position: absolute
  top: 1px
  right: 1px
  opacity: 0
  trans()
  &:hover
    color: $color-hover
    background: bgcolor($color-hover)

.highlight:hover .btn-copy
  opacity: 1

.article pre:hover .btn-copy
  opacity: 1