マウスオーバーで下にボーダー出す

.global-nav li a {
	position: relative;
	display: block;
  color: #fff;
	padding: 20px 30px;
}
.global-nav li a::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 100%;
  height: 1px;
  -webkit-transform: scaleX(0);
  -ms-transform: scaleX(0);
  transform: scaleX(0);
  background-color: rgba(255,255,255,0.5);
  -webkit-transition: all .3s ease;
  transition: all .3s ease;
}
.global-nav li a:hover::after {
  -webkit-transform: scaleX(1);
  -ms-transform: scaleX(1);
  transform: scaleX(1);
}