[Support request] Container block adds unwanted space

I’ve used a simple container block to highlight a section with a background color: http://www.lamppostsites.com (Caregiver Coaching). The “add new block” icon under that paragraph is adding unwanted space at the bottom. I reduced bottom padding to 0 but space remains. At one point I managed to “click off” it and the space disappeared, but when I went back to add the padding it reappeared.

I’m new to Gutenberg, so forgive me if this is something obvious. Thanks.