*, *:after, *:before { -webkit-box-sizing: border-box; -moz-box-sizing: border-box; box-sizing: border-box; }
body, html { font-size: 100%; padding: 0; margin: 0; height: 100%;}

.bb-custom-wrapper {
	width: 80%;
	height: 100%;
	margin: 0 auto;
	position: relative;
}

.bb-custom-wrapper .bb-bookblock {
	width: 1000px;
	height: 100%;
	-webkit-perspective: 2000px;
	perspective: 2000px;
}

.bb-custom-side {
	width: 50%;
	float: left;
	height: 100%;
	overflow: hidden;
	background: #fff;
	/* Centering with flexbox */
	display: -webkit-box;
	display: -moz-box;
	display: -webkit-flex;
	display: flex;
	-webkit-flex-direction: row;
	flex-direction: row;
	-webkit-flex-wrap: wrap;
	flex-wrap: wrap;
	-webkit-box-pack: center;
	-moz-box-pack: center;
	-webkit-justify-content: center;
	justify-content: center;
	-webkit-box-align: center;
	-moz-box-align: center;
	-webkit-align-items: center;
	align-items: center;
}

.bb-custom-wrapper > nav {
	/*width: 100%;
	height: 40px;
	margin: 1em auto 0;
	position: fixed;
	bottom: 20px;
	z-index: 1000;
	text-align: center;
	border: 1px solid blue;*/
	width: 1010px;
	position: absolute;
	margin: 0 auto;
	margin-top: -20px;
	//border: 1px solid blue;
	//text-align: center;
	z-index: 1000;
}

.promo_button_left, .promo_button_left:focus {
	position: absolute;
	width: 500px;
	float: left;
	margin-left: 4px;
	//border: 1px solid blue;
	border-left: 1px solid RGB(162, 0, 10);
	border-bottom: 1px solid RGB(162, 0, 10);
	background-color: RGB(65, 65, 65);
	color: white;
	text-align: center;
}

.promo_button_right, .promo_button_right:focus {
	position: absolute;
	margin-left: 504px;
	width: 500px;
	//border: 1px solid blue;
	border-right: 1px solid RGB(162, 0, 10);
	border-bottom: 1px solid RGB(162, 0, 10);
	background-color: RGB(65, 65, 65);
	color: white;
	text-align: center;
}

.promo_button_left:hover, .promo_button_right:hover {
	background-color: RGB(121, 131, 129);
	color: white;
	transition: all 0.5s linear;
}

/* No JS */
.no-js .bb-custom-wrapper {
	height: auto;
}

.no-js .bb-custom-content {
	height: 470px;
}

@media screen and (max-width: 61.75em){
	.bb-custom-side {
		font-size: 70%;
	}
}

@media screen and (max-width: 33em){
	.bb-custom-side {
		font-size: 60%;
	}
}