In response to @A.M.K's question about how to do transitions without jQuery. A very simple example I threw together. If I had time to think this through some more, I might be able to eliminate the JavaScript code altogether:
<style>
body {
background-color: red;
transition: background-color 2s ease-in;
}
</style>
<script>
window.onload = function() {
document.body.style.backgroundColor = '#00f';
}
</script>
<body>
<p>test</p>
</body>