looking to make my navigation bar turn semitransparent when I scroll the page, to do this, I know I'll need to edit the ID header, and turn that to an rgba, however, how do I make it so that when I scroll down the page, my header becomes semitransparent? Some kind of JavaScript or jQuery I presume, anyway, here's my code, can anyone guide me?
<header id="header">
<div class="container">
<div class="main">
<div class="logo">
<a href="index.html"><div class="top-logo"></div></a>
</div>
<nav>
<ul>
<li><a href="index.html" class="active">Home<span class="border"></span></a></li>
<li><a href="my-portfolio.html">My Portfolio<span class="border"></span></a></li>
<li><a href="about-me.html">About & Contact<span class="border"></span></a></li>
</ul>
</nav>
</div>
</div>
</header>
#header {
position: fixed;
display: block;
width: 100%;
top: 0;
height: 77px;
z-index: 9;
min-width: 320px;
background: #EFEFEF;
}