*{
	margin: 0;
	padding: 0;
	font-family: sans-serif;
	list-style: none;
	text-decoration: none;
}

.middle{
	position: absolute;
	top: 50%;
	left: 50%;
	transform: translate(-50%,-50%);
}
.menu{
	width: 300px;
	border-radius: 8px;
	overflow: hidden;
}
.item{
	border-top: 1px solid #2980b9;
	overflow: hidden;
}
.btn{
	display: block;
	padding: 16px 20px;
	background: #3498db;
	color: white;
	position: relative;
}
.btn:before{
	content: "";
	position: absolute;
	width: 14px;
	height: 14px;
	background:#3498db;
	left: 20px;
	bottom: -7px;
	transform: rotate(45deg);
}
.btn i{
	margin-right: 10px;
}
.smenu{
	background: #333;
	overflow: hidden;
	transition: max-height 0.3s;
	max-height: 0;
}
.smenu a{
	display: block;
	padding: 16px 26px;
	color: white;
	font-size: 14px;
	margin: 4px 0;
	position: relative;
}
.smenu a:before{
	content: "";
	position: absolute;
	width: 6px;
	height: 100%;
	background: #3498db;
	left: 0;
	top: 0;
	transition: 0.3s;
	opacity: 0;
}
.smenu a:hover:before{
	opacity: 1;
}
.item:target .smenu{
	max-height: 10em;
}