CSS/リストメニューwidth100%

#menu {
  list-style-type: none;
  width: 100%;
  margin: 50px auto 150px;
  padding: 0;
  border-top: 5px solid #888;
  border-bottom: 50px groove #555;
}
#menu li {
  position: relative;
  width: 19.9%;
  float:left;
  text-align: center;
}
#menu li a {
  color:#fff;
  font-size:15px;
  font-weight: normal;
  text-shadow:-1px -1px 0px #333,-1px 2px 0px #555;
  padding: 10px 0;
  text-decoration:none;
  display:block;
  background:#666;
}
#menu li a:hover {
	background: white;
	color: #333;
	text-shadow: 0px 0px 0px;
	transition: 0.3s;
}
#menu li:first-child {
	border-right: 1px solid white;
}
#menu li:nth-child(2){
	border-right: 1px solid white;
}
#menu li:nth-child(3){
	border-right: 1px solid white;
}
#menu li:nth-child(4){
	border-right: 1px solid white;
}