.flex {
  width: 50vw;
  height: 80px;
  line-height: 80px;
  background-color: white;
  position: relative;
  margin: 0 auto;
}

.flex ul {
  display: flex;
  padding: 0;
  margin: 0;
  box-shadow: 0 10px 20px 0 rgba(0, 0, 0, 0.25);
}

.flex ul li {
  flex: 1;
  list-style: none;
  text-align: center;
  position: relative;
  font-size: 20px;
  font-weight: bold;
  transition: 0.5s ease;
  cursor: pointer;
  user-select: none;
}

.flex ul li:hover {
  background-color: rgba(255, 255, 255, 0.25);
  color: #f564a9;
}

.flex ul li a {
  display: block;
  color: inherit;
  text-decoration: none;
}

.flex ul .bar {
  width: 20%;
  background-color: #af2850;
  height: 5px;
  position: absolute;
  left: 0;
  bottom: 0;
  transition: 0.5s ease;
}