<!DOCTYPE HTML>
<html>
<head>
<title>Untitled</title>
<meta charset="utf-8">
<style type="text/css">
body {
height: 2000px;
}
.orange {
background: #FFCC00;
}
.orange + div{
display: block;
}
span {
cursor: pointer;
}
#header{
bottom: 0px;
position: absolute;
}
</style>
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.11.0/jquery.min.js"></script>
<script>
$(function(){
var elem = $("#header"), h = elem.offset().top;
$(window).scroll(function(){
var top = $(this).scrollTop();
elem.css('top', top > h ? top : h )
});
});
</script>
</head>
<body>
<div id='header'>
<div class='first'>
<span class='info orange'>Информация</span>
<div class='main'>
<span class='info_show show '>текст1</span>
</div>
</div>
<div class='first'>
<span class='info'>Информация2</span>
<div class='main'>
<span class='info_show '>текст2</span>
</div>
</div>
<div class='first'>
<span class='info'>Информация3</span>
<div class='main'>
<span class='info_show '>текст3</span>
</div>
</div>
</div>
</body>
</html>