<div id="site-content"> 
  
  <p>
  MERHABA
  </p>
  
</div>

.tekrar p{background-color:red;color:white;}
if (/(^|;)\s*visited=/.test(document.cookie)) { 
    //alert("Hello again!");
var d = document.getElementById("site-content");
d.className += " tekrar";
	
} else {
    document.cookie = "visited=true; max-age=" + 60 * 60 * 24 * 10; 
    //alert("This is your first time!");
	
} 

External CSS

  1. https://codepen.io/wolkanca/pen/wvgOPWb

External JavaScript

  1. https://codepen.io/wolkanca/pen/wvgOPWb