Make a nav bar stick

Question

$(document).ready(function() {
  
  $(window).scroll(function () {
      //if you hard code, then use console
      //.log to determine when you want the 
      //nav bar to stick.  
      console.log($(window).scrollTop())
    if ($(window).scrollTop() > 280) {
      $('#nav_bar').addClass('navbar-fixed');
    }
    if ($(window).scrollTop() < 281) {
      $('#nav_bar').removeClass('navbar-fixed');
    }
  });
});

html, body {
	height: 4000px;
}

.navbar-fixed {
    top: 0;
    z-index: 100;
  position: fixed;
    width: 100%;
}

#body_div {
	top: 0;
	position: relative;
    height: 200px;
    background-color: green;
}

#banner {
	width: 100%;
	height: 273px;
    background-color: gray;
	overflow: hidden;
}

#nav_bar {
	border: 0;
	background-color: #202020;
	border-radius: 0px;
	margin-bottom: 0;
    height: 30px;
}

.nav_links {
    margin: 0;
}

.nav_links li {
	display: inline-block;
    margin-top: 4px;
}
.nav_links li a {
	padding: 0 15.5px;
	color: #3498db;
	text-decoration: none;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div id="banner">
     <h2>put what you want here</h2>
     <p>just adjust javascript size to match this window</p>
  </div>

  <nav id='nav_bar'>
    <ul class='nav_links'>
      <li><a href="url">Nav Bar</a></li>
      <li><a href="url">Sign In</a></li>
      <li><a href="url">Blog</a></li>
      <li><a href="url">About</a></li>
    </ul>
  </nav>
<div id='body_div'>
    <p style='margin: 0; padding-top: 50px;'>and more stuff to continue scrolling here</p>
</div>

add to your .nav css block the

position: fixed

and it will work

I hope this can help someone. Determine the nav offset through js and then apply sticky position css to nav:

But first, we will define the styles in the stylesheet, like so.

.sticky {
    position: fixed;
    width: 100%;
    left: 0;
    top: 0;
    z-index: 100;
    border-top: 0;
}

Then, we will apply that class to the navigation conditionally with jQuery.

$(document).ready(function() {
  var stickyNavTop = $('.nav').offset().top;

  var stickyNav = function(){
    var scrollTop = $(window).scrollTop();

    if (scrollTop > stickyNavTop) { 
      $('.nav').addClass('sticky');
    } else {
      $('.nav').removeClass('sticky'); 
    }
  };

  stickyNav();

  $(window).scroll(function() {
    stickyNav();
  });
});

Just use z-index CSS property as described in the highest liked answer and the nav bar will stick to the top.

Example:

<div class="navigation">
 <nav>
   <ul>
    <li>Home</li>
    <li>Contact</li>
   </ul>
 </nav>

.navigation {
   /* fixed keyword is fine too */
   position: sticky;
   top: 0;
   z-index: 100;
   /* z-index works pretty much like a layer:
   the higher the z-index value, the greater
   it will allow the navigation tag to stay on top
   of other tags */
}

CSS:

.headercss {
    width: 100%;
    height: 320px;
    background-color: #000000;
    position: fixed;
}

Attribute position: fixed will keep it stuck, while other content will be scrollable. Don't forget to set width:100% to make it fill fully to the right.

Example

Give headercss position fixed.

.headercss {
    width: 100%;
    height: 320px;
    background-color: #000000;
    position: fixed;
    top:0
}

Then give the content container a 320px padding-top, so it doesn't get behind the header.