menu_width = 135;
menu_pos_top = "150px";
menu_sidetype = "left"; // left or right
selector_menu = ".sidemenu";
selector_contents = ".contents-body";
function initSideMenu() {
	var sheet = document.styleSheets.item(1);
	addRule(sheet, selector_menu, "position: absolute");
	addRule(sheet, selector_menu, "top: " + menu_pos_top);
	addRule(sheet, selector_menu, "border-" + menu_sidetype + ": none");
	hideSideMenu();
}
function showSideMenu() {
	var sheet = document.styleSheets[0];
	addRule(sheet, selector_menu, menu_sidetype + ": 0");
}
function hideSideMenu() {
	var sheet = document.styleSheets[0];
	addRule(sheet, selector_menu, menu_sidetype + ": -" + (menu_width-10) + "px");
}
function addRule(sheet, selector, property) {
	if (sheet.addRule) { // IE
		sheet.addRule(selector, property);
	} else if (sheet.insertRule) { // Fx
		sheet.insertRule(selector + "{" + property + "}", sheet.cssRules.length);
	} else { // others
		// nothing to do.
	}
}