#about_us {
	width: 900px;
	margin-right: auto;
	margin-left: auto;
	clear: both;
}
.prodct_list {
	width: 900px;
	margin-right: auto;
	margin-left: auto;
}
.prodct_list li {
	list-style-type: square;
	margin-left: 25px;
}