The template includes various .css files, which is why you see the border. It is defined in base2.css in L337 and L372 (focused). To remove it, remove these definitions (or adjust them to your liking).
Thanks - I just tried that and it removes the two boxes around the dates. Ideally I’d like to remove the outer box that goes around the two date boxes (apologies - in hindsight it wasn’t clear in my OP!). Any ideas on that one? I’ve tried commenting out anything referring to “border : 1px” in base2.css but it won’t go!