body {
  background: #2c3e50;
}

#nav {
  position: relative;
  margin: 45vh auto 0;
  width: 590px;
  height: 50px;
  background: #34495e;
  border-radius: 8px;
  font-size: 0;
  box-shadow: 0 2px 3px 0 rgba(0, 0, 0, 0.3);
}

#nav a {
  font-size: 16px;
  text-transform: uppercase;
  color: white;
  text-decoration: none;
  line-height: 50px;
  position: relative;
  z-index: 1;
  display: inline-block;
  text-align: center;
}

#nav .animation {
  position: absolute;
  height: 100%;
  /* height: 5px; */
  top: 0;
  /* bottom: 0; */
  z-index: 0;
  background: #09c372;
  border-radius: 8px;
  transition: all 0.5s ease 0s;
}
#nav a:nth-child(1) {
  width: 100px;
}
#nav .start-home,
a:nth-child(1):hover ~ .animation {
  width: 100px;
  left: 0;
}
#nav a:nth-child(2) {
  width: 110px;
}
#nav a:nth-child(2):hover ~ .animation {
  width: 110px;
  left: 100px;
}
#nav a:nth-child(3) {
  width: 100px;
}
#nav a:nth-child(3):hover ~ .animation {
  width: 100px;
  left: 210px;
}
#nav a:nth-child(4) {
  width: 160px;
}
#nav a:nth-child(4):hover ~ .animation {
  width: 160px;
  left: 310px;
}
#nav a:nth-child(5) {
  width: 120px;
}
#nav a:nth-child(5):hover ~ .animation {
  width: 120px;
  left: 470px;
}