JSFiddle - React, Tailwind, and code Playground

HTML

<html>
<body>
    <div id="header"></div>
</body>
</html>

CSS

#header {
    border: 1px solid green;
    height: 256px;
    width: 256px;
}

.image1 {
    background-image: url('http://images4.wikia.nocookie.net/__cb20100429000907/jamescameronsavatar/images/e/e5/Google_Chrome_Icon.png');
}

.image2 {
    background-image: url('http://pingvinoff.net/wp-content/uploads/2011/05/chroms.png');
}

JavaScript

setInterval(function(){
   var m = new Date();
   var time = m.getSeconds();
   if (time == 19 || time == 39 || time == 59) {
      document.getElementById('header').className = 'image1';
   } else if (time == 15 || time == 30 || time == 45) {
      document.getElementById('header').className = 'image2';
   }
}, 1000)