// カバー表示
function viewCover(){
	var offsetWidth = document.body.offsetWidth != "" ? document.body.offsetWidth : document.documentElement.offsetWidth;
	var coverWidth = document.documentElement.clientWidth > offsetWidth ? document.documentElement.clientWidth : offsetWidth;
	
	var offsetHeight = document.body.offsetHeight != "" ? document.body.offsetHeight : document.documentElement.offsetHeight;
	var coverHeight = document.documentElement.clientHeight > offsetHeight ? document.documentElement.clientHeight : offsetHeight;
	
	$("cover").style.width = coverWidth + 'px';
	$("cover").style.height = coverHeight + 'px';
	$("cover").style.display = "block";
	
	$("cover_caution").style.left = ((document.documentElement.clientWidth / 2) - ($("cover_caution").style.width.replace(/px$/i,'') / 2)) + "px";
	$("cover_caution").style.top = ((document.documentElement.clientHeight / 2) - ($("cover_caution").style.height.replace(/px$/i,'') / 2)) + "px";
	$("cover_caution").style.display = "block";
}