Change font size of the nbconverted html output

I coded a table with TABLE.to_markdown(). When I use nbconvert to convert ipynb to html output, the table with only five columns takes pretty much whole page width, which is disturbing when printed.

I tried to use nbconvert “–template” method and tried to work on the basic/full.tpl from /…/nbconvert/templates/html/, but did not manage to change/reduce the font size of the HTML output. Have also googled it extensively and checked on nbconvert github repository, but did not find any proper solution, at least not based on my limited knowledge. I would appreciate some help on how to define the font size in e.g. full.tpl template in order to get smaller font-size of the output HTML file.