since you're using jquery anyways it would be easier for the dom and maybe for you too to use data attributes and [$.data](https://api.jquery.com/data/#data). I think this would require less change for new attributes as well.
e.g. something like
```js
hbr.append('<div id="ExtensionInfo" style="display:none;" data-key="'+profile.key+'" data-email="'+profile.email+'"></div>');
```
and then in the injected script the relevant part becomes

```js
var user = $('#ExtensionInfo').data();
```
Also no reason not to put the style in the css files right? No strong arguement against inline either though.