JSFiddle - React, Tailwind, and code Playground

HTML

<div id="demo" style="background-color: #0f0; color: purple; -moz-transition: all 1s linear;" class="stuff">One</div>
<div id="demo2">Two</div>

CSS

.stuff {
    width: 15em;
    height: 32px;
    position: relative;
    background-color: blue;
}

JavaScript

function getCamel(str) {
    return str.replace(/^(-\w)/, function(m) {
        return m.substring(1).toLowerCase();
    }).replace(/(-\w)/g, function(m) {
        return m.substring(1).toUpperCase();
    });
}
function getAllStyles(elm) {
    var result = {};
    if(window.getComputedStyle) {
        var styles = window.getComputedStyle(elm, null);
        for(var i=0; i<styles.length; i++) {
            var val = styles.getPropertyValue(styles[i]);
            var key = getCamel(styles[i]);
            if(val != "")
                result[key] = val;
        }
    } else if(elm.style) {
        for(var i=0; i<elm.style.length; i++) {
            var key = getCamel(elm.style[i]);
            var val = elm.style[key];
            if(val != "")
                result[key] = val;
        }
    }    
    return result;
}
function copyAllStyles(srcElm, dstElm) {
    var styles = getAllStyles(srcElm);
    for(var key in styles)
        if(styles.hasOwnProperty(key)) {
            dstElm.style[key] = styles[key];
            if(key == "backgroundColor")
            console.log(key, styles[key], dstElm.style.backgroundColor);
        }
}

var src = document.getElementById("demo");
var dst = document.getElementById("demo2");
window.setTimeout(function(){
    copyAllStyles(src, dst);
}, 2000);