* {
	margin: 0;
	padding: 0;
	box-sizing: border-box;
}

body {
	text-align: center;
	background-image: url('img/wood.jpg');
	background-size: cover;
	width: 100%;
	height: 100vh;
	overflow: hidden;
}

#start {
	display: inline-block;
	margin-top: 30vh;
	background-color: rgba(255,255,255,0.3);
	padding: 40px;
	text-align: right;
}

#start label {
	display: block;
	color: #333;
	margin: 15px 0;
	border-radius: 20px;
}

#start select {
	width: 200px;
	display: inline-block;
	padding: 5px 10px;
	vertical-align: middle;
	border-top-right-radius: 20px;
	border-bottom-right-radius: 20px;
}

#start h2 {
	padding: 5px;
	font-size: 16px;
	display: inline-block;
	vertical-align: middle;
	font-weight: normal;
	text-align: center;
	width: 150px;
	border-top-left-radius: 20px;
	border-bottom-left-radius: 20px;
	border: none;
	box-shadow: 1px 2px 3px 0 #888;
	background-color: #f5f5f5;
}

#start-game {
	margin-top: 30px;
	display: block;
	width: 100%;
	padding: 8px;
	background-color: #f5f5f5;
	border-radius: 20px;
	border: none;
	box-shadow: 1px 2px 3px 0 #888;
}

#start-game:active {
	background-color: #fff;
}

#container {
	visibility: hidden;
	display: flex;
	flex-direction: column;
	flex-wrap: wrap;
	width: 98%;
	height: 98vh;
	margin: 1vh auto;
	perspective: 1000px;
}

.row {
	flex: 1;
	display: flex;
	flex-direction: row;
}

.card {
	transition: transform 1s ease;
	backface-visibility: hidden;
	width: 100%;
	height: 100%;
	position: absolute;
}

.card-holder {
	margin: 5px;
	flex: 1;
	position: relative;
}

.card.-front {
	background-size: contain;
	background-repeat: no-repeat;
	background-position: center;
}

.card.-back {
	background-size: contain;
	background-repeat: no-repeat;
	background-position: center;
}

.card-holder.reverse .card.-front {
	transform: rotateY(-0.5turn);
}

.card-holder.reverse .card.-back {
	transform: rotateY(0turn);
}

.-flipped {
	transform: rotateY(0.5turn);
}

.shake {
	animation: shake 0.82s cubic-bezier(.36,.07,.19,.97) both;
	transform: translate3d(0, 0, 0);
	backface-visibility: hidden;
	perspective: 1000px;
}

@keyframes shake {
	10%, 90% {
		transform: translate3d(-1px, 0, 0);
	}

	20%, 80% {
		transform: translate3d(2px, 0, 0);
	}

	30%, 50%, 70% {
		transform: translate3d(-4px, 0, 0);
	}

	40%, 60% {
		transform: translate3d(4px, 0, 0);
	}
}

@media screen and (max-width: 700px) {

	#start {
		background-color: unset;
	}

	#start select {
		width: 120px;
	}

	#start h2 {
		width: 120px;
	}

}