@charset "utf-8";
/* CSS Document */

* {
	margin:0;
	padding:0;
}
 
body {
	background:#FFFFFA;
	font-family:  Helvetica, Arial, sans-serif;
	font-size: 10px;
	font-style: normal;
	font-weight: normal;
	overflow: auto;
}
 
header {
	width:100%;
}
 
header nav {
	width:20%;
	max-width:500px;
	float:right;
	margin:40px auto;
	background: #FFF;
}
 
.menu_bar {
	display:none;
}
 
header nav ul {
	overflow:hidden;
	list-style:none;
}
 
header nav ul li {
	float:left;
}
 
header nav ul li a {
	color: #CCC;
	padding:8px;
	text-align:center;
	display:block;
	text-decoration:none;
}
 
header nav ul li span {
	margin-right:10px;
}
 
header nav ul li a:hover {
	color: #F00;
}
 
section {
	padding:20px;
}
 
.logo {
	position:absolute;
	left:8%;
	width:220px;
	height:40px;
	top: 24px;
}

.logomovil {
	display:none;
}

.text1 {
	position:absolute;
	width:20%;
	height:90%;
	right:0;
	z-index:-1;
	top: 80px;
	overflow: auto;
	overflow-x:hidden;
}

.slider {
	position:absolute;
	width:77%;
	height:85%;
	z-index:-1;
	top: 80px;
}

.tira {
	position:absolute;
	width:100%;
	height:40px;
}
 
@media screen and (max-width:800px ) {
	body {
		font-size: 8px;
		overflow: auto;
	}
	
	.text1 {
		width:95%;
		height:auto;
		overflow:auto;
		top:500px;
	}
	
	.slider {
		width:90%;
		top:auto;
	}
	
	.logo {
		display:none;
	}
	
	.logomovil {
	display:block;
	position:absolute;
	left:8%;
	width:165px;
	height:30px;
	top: 30px;
	}
	
	header nav {
		max-width:800px;
		width:100%;
		height:17.8%;
		left:-100%;
		margin:0;
		position: relative;
	}
 
	header nav ul li {
		display:block;
		float:none;
		border-bottom:1px solid rgba(0,0,0, .3);
	}
 
	.menu_bar {
		display:block;
		width:100%;
		background:#ccc;
	}
 
	.menu_bar .bt-menu {
		display:block;
		padding:25px;
		background: #FFF;
		color: #999;
		text-decoration:none;
		font-weight: lighter;
		font-size:25px;
		-webkit-box-sizing:border-box;
		-moz-box-sizing:border-box;
		box-sizing:border-box;
	}
 
	.menu_bar span {
		float:right;
		font-size:40px;
	}
}

Código Javascript: