JSFiddle - React, Tailwind, and code Playground

HTML

<body id="full">
<form method="post" action="">

Background:<input type="text" class="theme" id="background"/>
    eg. type black  or color code
    </form>
</body>

CSS

#full {

 background-color: #ffffff;
}

JavaScript

$(document).ready(function(){
    
    $(".theme").keyup(function()
    {
    
    var background = $("#background").val();
    
    
    $("#full").css("background-color", background);
    });
    
    });