erpnext/website/css/website.css

#body_div {
	width: 900px;
	margin: auto;
}

header .topbar .container {
	width: 900px;
	margin: auto;
}

.web-main-section {
	width: 65%;
	float: left;
	margin-bottom: 20px;
}

.web-side-section {
	width: 30%;
	float: right;
	margin-bottom: 20px;
}