.btn {
	padding:0px;
	width:100px;
	height:40px;
	position:relative;
	cursor:pointer;
	font-size:20px;
	line-height:40px;
	text-align:center;
}
.btn::after,.btn::before {
	content:"";
	border:2px solid #333;
	display:block;
	width:50px;
	height:20px;
}
.btn::after {
	position:absolute;
	bottom:0px;
	right:0px;
	border-top-color:transparent;
	border-left-color:transparent;
}
.btn::before {
	position:absolute;
	top:0px;
	left:0px;
	border-bottom-color:transparent;
	border-right-color:transparent;
}
.btn:hover::after,.btn:hover::before {
	content:"";
	border:2px solid #333;
	display:block;
	width:110px;
	height:50px;
	transition:all 0.5s ease;
}
.btn:hover::after {
	position:absolute;
	bottom:0px;
	right:0px;
	border-top-color:transparent;
	border-left-color:transparent;
}
.btn:hover::before {
	position:absolute;
	top:0px;
	left:0px;
	border-bottom-color:transparent;
	border-right-color:transparent;
}
.nav {
	width:300px;
	height:40px;
	margin:0px auto;
}
.nav ul {
	padding:0px;
	width:100%;
}
.nav ul:after {
	content:"";
	width:0px;
	height:0px;
	display:block;
	visibility:hidden;
	clear:both;
}
.nav li {
	position:relative;
	width:100px;
	float:left;
	list-style:none;
	height:40px;
	line-height:40px;
	text-align:center;
	font-size:16px;
	transition:all 0.5s ease;
}
.nav li:hover {
	color:red;
	font-size:18px;
}
.nav li::after {
	content:"";
	width:0%;
	height:40px;
	display:block;
	border-bottom:2px solid #333;
	position:absolute;
	top:0px;
	left:45px;
	transition:all 0.5s ease;
}
.nav li:hover::after {
	content:"";
	width:100%;
	height:40px;
	display:block;
	border-bottom:2px solid #333;
	position:absolute;
	top:0px;
	left:0px;
}
.nav a {
	text-decoration:none;
	color:#333;
}
.pie {
	position:relative;
}
.bg {
	width:100px;
	height:100px;
	border:0px;
	border-radius:50px;
	background-color:brown;
	position:absolute;
	top:0px;
	left:0px;
}
.left {
	width:50px;
	height:100px;
	background-color:forestgreen;
	border-left:0px solid forestgreen;
	border-top-left-radius:50px;
	border-bottom-left-radius:50px;
	float:left;
	position:absolute;
	top:0px;
	left:0px;
}
.right {
	width:50px;
	height:100px;
	background-color:forestgreen;
	border-left:0px solid forestgreen;
	border-top-right-radius:50px;
	border-bottom-right-radius:50px;
	float:left;
	transform:rotate(0deg);
	transform-origin:0% 50%;
	transition:transform 0.5s ease;
	position:absolute;
	top:0px;
	left:50px;
}
.right:hover {
	transform:rotate(90deg);
	transform-origin:0% 50%;
}