file.js

setTimeout(function() {
	[].forEach.call(chat.querySelectorAll('.user-container .message'), visualHexColors);
}, 1000); // some users are never parsed. this solves that. (I have other shit in the timeout) 
new MutationObserver(function(records) {
	records.forEach(function(record) {
		[].forEach.call(record.addedNodes, visualHexColors);
	});
}).observe(chat, {
	childList: true,
	subtree: true
});
function visualHexColors(node) {
    if (node.classList && node.classList.contains('message') && !node.classList.contains('pending')) {
        [].forEach.call(node.childNodes, function(child) {
            if (/#(?:[0-9a-f]{3}){1,2}/ig.test(child.textContent)) {
                child.innerHTML = child.innerHTML.replace(/#(?:[0-9a-f]{3}){1,2}/ig, function(match) {
                    return '<span style="width:12px;height:12px;border:1px solid #222;background-color:' + match + ';display:inline-block;"></span>' + match;
                });
            }
        });
    }
}