[Plugin: phpbb_recent_topics] CSS?

Anyone know of a way I can modify the results to make them a bit more “appealing” with CSS rather than having them as a plain list?

I’d like to add some background colour, change the font colour etc…?

I’ve tried adding a <span class> to the “echo” lines but it just throws up an error saying there’s an unexpected “<” in them lines. So where can I put the CSS Class to change the way the results appear on my site?