To ensure a consistent design the customer care department asked for help to make the LiveChat relatable to our brand. Since they had no capacity available to deal with it I took over that task. Before having a look at the stylesheet I designed a look that fitted into the corporate design.
The LiveChat itself is an integrated SalesForce tool. A colleague set up an account that I could use for test purposes only. So I was able to check what the styling looked like from both agent's and client's view. One annoying problem was the rather limited access to any stylesheet (thanks to SalesForce). But in the end I managed to implement every style I created.
The SalesForce chat itself worked already responsive. So I only had to adjust my own styles to make them work on mobile view.