Basic css to get a Liferay "unstyled" theme up and running for 6.0

custom.css

/* -------- Global -------- */

#skip-to-content,
#heading .community-title,
#heading .page-title,
#navigation h1,
#navigation .child-menu,
#breadcrumbs {
	clip: rect(0 0 0 0);
	height: 0;
	margin: 0;
	padding: 0;
	position: absolute;
}

body {
	background: #CCC;
	font-family: Arial, Helvetica, sans-serif;
	font-size: 12px/1;
}

#wrapper {
	background: #FFF;
	margin: 0 auto;
	padding: 5px;
	width: 960px;
}

/* -------- Sign-in / Navigation -------- */

#sign-in {
	position: absolute;
	right: 0;
	top: 0;
}

#navigation ul {
	display: inline-block;
	margin: 0;
}

#navigation li {
	background: #DDD;
	display: block;
	float: left;
	padding: 5px;
}

#navigation li a {
	text-decoration: none;
}

/* -------- Web Content -------- */