Margins within table cells

I am using Catch Box theme and using block (Gutenberg?) tables created on the latest Wordpress. The margins above and below text within cells are too large. Other themes seem to have smaller margins, so I presume that the margin settings are determined by the theme rather than by Wordpress's block system. What part of Catch Box's CSS holds the margin settings? (I am familiar with CSS coding but cannot find them.) Thanks David (davidparton.co.uk)