part.scss

.border {	
  position: absolute;	
  top: -4px;	
  left: -4px;	
  transform: translate(-20px, -20px);	
  transition: transform;	
  transition-duration: 0.1s;	
  border-style: solid;	
  border-width: 1px;	
  border-color: red;	
  width: 8px;	
  height: 8px;	

  &--leftTop {	
    transform: translate3d(-20px, -20px, 1px);	
    border-bottom-color: transparent;	
    border-right-color: transparent;	
  }	
  &--leftBottom {	
    transform: translate3d(-20px, calc(100vh + 20px), 1px);	
    border-top-color: transparent;	
    border-right-color: transparent;	
  }	
  &--rightTop {	
    transform: translate3d(calc(100vw + 20px), -20px, 1px);	
    border-bottom-color: transparent;	
    border-left-color: transparent;	
  }	
  &--rightBottom {	
    transform: translate3d(calc(100vw + 20px), calc(100vh + 20px), 1px);	
    border-top-color: transparent;	
    border-left-color: transparent;	
  }	
}