[SOLVED] How can i change color of top fixed navbar in bootsrap 4?

How can i change color of top fixed navbar in bootsrap 4?

Hi I am new to web development. I have a problem with navbar in bootstrap 4 beta while changing the color. How can I change the color of a fixed navigation bar while scrolling in bootstrap 4 beta. And please consider any tutorial about this.

Solution

i given some idea,just this is an example,

$(document).ready(function(){
  $(window).scroll(function(){
  	var scroll = $(window).scrollTop();
	  if (scroll > 300) {
	    $(".black").css("background" , "blue");
	  }

	  else{
		  $(".black").css("background" , "#333");  	
	  }
  })
})

body{
  margin:0;
  padding:0;
  height:1000px;
}
.black{
  position:fixed;
  top:0;
  background:#333;
  width:100%;
  height:50px;
  
}
.black ul{
  list-style-type:none;
  padding:0;
}

.black ul li{
  display:inline-block;
  width:100px;
  color:red;
}

.blue{
  position:fixed;
  top:0;
  background:blue;
  width:100%;
  height:50px;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<div class="black">
  <ul>
    <li>link</li>
    <li>link</li>
    <li>link</li>
    <li>link</li>
  </ul>
</div>