style.css

 

*{
  margin: 0;
  padding: 0;
}
.main-menu{
  padding: 80px 20px;
  font-family: serif;
}
.menu{
  background: #8162bb;
}

.main-menu ul{
  list-style: none;
  margin: 0;
  padding: 0;
  text-align: center;
}
.main-menu li{
  display: inline-block;
  margin: 0 15px;
}
.main-menu a{
  font-size: 22px;
  text-transform: uppercase;
  text-decoration: none;
  color: #fff;
  display: block;
  position: relative;
  padding: 4px 0;
}
.main-menu a::before{
  content: "";
  width: 100%;
  height: 4px;
  position: absolute;
  left: 0;
  bottom: 0;
  background: #fff;
  transition: 0.5s transform ease;
  transform: scale3d(0,1,1);
  transform-origin: 0 50%;
}
.main-menu a:hover::before{
  transform: scale3d(1,1,1);
}
.menu a::before{
  background: #f9f4f4;
  transform-origin: 100% 50%;
}
.menu a:hover::before{
  transform-origin: 0 50%;
}