A webpage header can be fixed at the top of the page using CSS and jQuery. The best way to do this is to set a new CSS class for the fixed position that will get assigned to the relevant div when scrolling goes past a certain point.
Additionally, you may have to assign css z-index to either the header or content div to prevent overlaying content over the header as it is scrolled.
HTML
<div class="header"></div>
<div id="content">
...
</div>
CSS
.fixed {
position: fixed;
top:0; left:0;
width: 100%;
}
#content {
z-index: -99;
}
jQuery
$(window).scroll(function(){
var header = $('.header'),
scroll = $(window).scrollTop();
if (scroll >= 100) header.addClass('fixed');
else sticky.removeClass('fixed');
});