Идеальный PopUp на html+css?

.layout {
	width: 100%;
	height: 100%;
	position: fixed;
	left: 0;
	top: 0;
	background: rgba(0,0,0,0.5);
}

.layout__inner {
	width: 400px;
	position: absolute;
	top: 50%;
	left: 50%;
	transform: translate(-50% -50%);
	background: #fff;
}