Background Macro Not Working?

I know you can use CSS to change the background, and my question is not about changing the background colour. However, in my story the background is black and the text is black. So, I need to have a white box behind the text. So, I knew to use the (background:) macro. When I last used it, however, it drew a box around all the text in the square brackets. But when I recently used it, the background had spaces in between in writing, instead an entire box. Is this a bug? Do I remember this macro wrongly? Is there another way I can do this? I am using Harlowe.
Thanks.