Edit in JSFiddle

<ul class="navigation">
  <li><a href="#">Link 1</a></li>
  <li><a href="#">Link 2</a></li>
  <li><a href="#">Link 3</a></li>
  <li><a href="#">Link 4</a></li>
</ul>
.navigation {
  padding: 0;
  width: 75%;
  display: flex;
  flex-flow: row nowrap;
  /* justify-content: space-between; */
  background: #007bff;
  border-radius: 1.5rem;
}

.navigation li {
  list-style: none;
  display: inline-block;
  width: 25%;
  text-align: center;
}

.navigation li a {
  display: inline-block;
  color: #fff;
  text-decoration: none;
  background: #007bff;
  width: 100%;
  padding: 0.75rem 0;
  border-radius: 1.5rem;
}

.navigation li a:hover {
  color: #333;
  background: #e7e7e7;
  transform: scale(1.25);
  font-size: 12.8px;
  transition: 0.25s linear;
  box-shadow: 0 0 0.2rem 0 #999;
}