*{
	box-sizing: border-box;
	margin: 0;
	padding: 0;
}
.contents{
	margin: 0 auto;
	max-width: 800px;
	padding: 60px;
}
.contents h1{
	margin-bottom: 60px;
	text-align: center;
}
.box{
	border: 2px dashed #ccc;
	height: 1000px;
	padding: 20px;
}
.box + .box{
	margin-top: 40px;
}
.sticky_container{
	border: 2px dashed #7f31d6;
}
.sticky_item{
	background: #fff;
	color: #7f31d6;
	position: sticky;
	top: 0;
}
.scroll_area{
	background: #ccc;
	margin-top: 60px;
	height: 1000px;
	padding: 40px;
}