.hover_sub {
  position: relative;
  display: inline-block;
  text-decoration: none;
}
.hover_sub::after {
  position: absolute;
  bottom: -4px;
  left: 0;
  content: '';
  width: 100%;
  height: 2px;
  background: #FFFFFF;
  transform: scale(0, 1);
  transform-origin: center top;
  transition: transform .3s;
}

.hover_sub:hover::after {
  transform: scale(1, 1);
}