function altrows() {
	var tables = document.getElementsByTagName('table');
	for (var i=0; i<tables.length; i++) {
		var theTable = tables[i];
		var allRows = theTable.getElementsByTagName('tr');
		if (theTable.className == 'holtables') {
			for (var j=1; j<allRows.length/*-2*/; j+=2) {
				var altRows = allRows[j];
				altRows.className = 'purple';
				allRows[0].className = 'head';
			}
		}
	}
}

window.onload = altrows;