div.page
{
	display: table;
	clear: both;
}

div.mainpane
{
	float: left;
	width: 25%;
}

div.subpane
{
	float: right;
	width: 75%;
}

div.page
{
	display: table;
	clear: both;
}

div.mainpane
{
	float: left;
	width: 50%;
}

div.subpane
{
	float: right;
	width: 50%;
}

Set both panes to half width
Http: Set both panes to half width
