* {
	margin:0;
	padding:0;
}
.box {
	width:50px;
	height:250px;
	margin:20px auto;
	animation:a 5s infinite linear;
	transform-origin:center top;
}
.span1 {
	width:20px;
	height:200px;
	background:#ccc;
	display:block;
	margin:0 auto;
}
.span2 {
	width:50px;
	height:50px;
	display:block;
	border-radius:50%;
	background:yellowgreen;
	margin-top:-2px;
}
@keyframes a {
	0%,100% {
	transform:rotate(-45deg);
}
20% {
	transform:rotate(15deg);
}
30% {
	transform:rotate(30deg);
}
40% {
	transform:rotate(45deg);
}
50% {
	transform:rotate(30deg);
}
60% {
	transform:rotate(15deg);
}
70% {
	transform:rotate(0deg);
}
80% {
	transform:rotate(-15deg);
}
90% {
	transform:rotate(-30deg);
}
}