How to fix a header on scroll

Question

I am creating a header that once scrolled to a certain amount of pixels it fixes and stays in place.

Can I do this using just css and html or do i need jquery too?

I have created a demo so you can understand. Any help would be great!

http://jsfiddle.net/gxRC9/4/

body{
    margin:0px;
    padding:0px;
}
.clear{
    clear:both;
}
.container{
    height:2000px;
}
.cover-photo-container{
width:700px;
height: 348px;
margin-bottom: 20px;
background-color:red;
}

.small-box{
    width:163px;
    height:100px;
    border:1px solid blue;
    float:left;
}

.sticky-header{
    width:700px;
    height:50px;
    background:orange;
    postion:fixed;
}

Answer 1

You need some JS to do scroll events. 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.

HTML

<div class="sticky"></div>

CSS

.fixed {
    position: fixed;
    top:0; left:0;
    width: 100%; }

jQuery

$(window).scroll(function(){
  var sticky = $('.sticky'),
      scroll = $(window).scrollTop();

  if (scroll >= 100) sticky.addClass('fixed');
  else sticky.removeClass('fixed');
});

Example fiddle: http://jsfiddle.net/gxRC9/501/

---

EDIT: Extended example

If the trigger point is unknown but should be whenever the sticky element reaches the top of the screen, offset().top can be used.

var stickyOffset = $('.sticky').offset().top;

$(window).scroll(function(){
  var sticky = $('.sticky'),
      scroll = $(window).scrollTop();

  if (scroll >= stickyOffset) sticky.addClass('fixed');
  else sticky.removeClass('fixed');
});

Extended example fiddle: http://jsfiddle.net/gxRC9/502/