.heart {
  position: relative;
  width: 20px;
  height: 20px;
  overflow: hidden;
}

.heart:before {
  position: absolute;
  content: '';
  display: block;
  top: -4px;
  left: 0px;
  width: 4px;
  height: 4px;
  box-shadow: 
    0px 8px, 
    4px 8px 0 0 red, 
    4px 12px 0 0 red, 
    4px 4px, 8px 8px, 
    8px 12px 0 0 red, 
    8px 16px 0 0 red, 
    12px 4px, 
    12px 8px 0 0 red, 
    12px 12px 0 0 red, 
    16px 8px, 
    16px 12px, 
    12px 16px, 
    8px 20px, 
    4px 16px, 
    0px 12px;
}