Site Styling Options
Clicking the Styler button will bring up more options, including more background colours and patterns.
Choose any thread, scroll down to the bottom and click the Styler button. There are options for typeface, text size, text background and text colour. Click the green tick symbol to save your choices.
Note these choices will only change the text in posts and conversations, so you need to be on a page that displays them in order to see any difference.