CSS3实现菜单悬停效果

<nav id="nav-1">
  <a class="link-1" href="#">home</a>
  <a class="link-1" href="#">about</a>
  <a class="link-1" href="#">contact</a>
  <a class="link-1" href="#">shop</a>
</nav>

<nav id="nav-2">
  <a class="link-2" href="#">home</a>
  <a class="link-2" href="#">about</a>
  <a class="link-2" href="#">contact</a>
  <a class="link-2" href="#">shop</a>
</nav>

<nav id="nav-3">
  <a class="link-3" href="#">home</a>
  <a class="link-3" href="#">about</a>
  <a class="link-3" href="#">contact</a>
  <a class="link-3" href="#">shop</a>
</nav>

@import url(https://fonts.googleapis.com/css?family=raleway);
body {
  margin: 0px;
}
nav {
  margin-top: 40px;
  padding: 24px;
  text-align: center;
  font-family: raleway;
  box-shadow: 2px 2px 8px rgba(0, 0, 0, 0.5);
}
#nav-1 {
  background: #3fa46a;
}
#nav-2 {
  background: #5175c0;
}
#nav-3 {
  background: #eea200;
}

.link-1 {
  transition: 0.3s ease;
  background: #3fa46a;
  color: #ffffff;
  font-size: 20px;
  text-decoration: none;
  border-top: 4px solid #3fa46a;
  border-bottom: 4px solid #3fa46a;
  padding: 20px 0;
  margin: 0 20px;
}
.link-1:hover {
  border-top: 4px solid #ffffff;
  border-bottom: 4px solid #ffffff;
  padding: 6px 0; 
}

.link-2 {
  transition: 0.6s;
  color: #ffffff;
  font-size: 20px;
  text-decoration: none;
  border-right: 2px dotted transparent;
  padding: 30px 8px 0 10px;
  margin: 0 10px;
}
.link-2:hover {
  border-right: 2px dotted #ffffff;
  padding-bottom: 24px;
}
.link-3 {
  transition: 0.4s;
  color: #ffffff;
  font-size: 20px;
  text-decoration: none;
  padding: 0 10px;
  margin: 0 10px;
}
.link-3:hover {
  background-color: #ffffff;
  color: #eea200;
  padding: 24px 10px;
}