The distinction can be difficult to make, but I think it is relatively clear here. I'm "reading between the lines" here so could be wrong, but "looks like your

The distinction can be difficult to make, but I think it is relatively clear here. I'm "reading between the lines" here so could be wrong, but "looks like your site is using a theme based on" implies to me that there is enough code (markup, styles, perhaps script) similarly that is enough to not be pure coincidence. That suggests using some of the code not just being inspired to produce a clean-room design, so the GPL is relevant.