How to fix calendar spacing?

In your child theme or using an CSS Editor..
you can play around with something like this..

table.fullcalendar td {
    min-width: 140px;
    max-width: 140px !important;
}

on a side note there is a companion plugin for the calendar..
WP Fullcalendar that makes a really nice calendar.
https://www.ads-software.com/plugins/wp-fullcalendar/

make sure you go into the calendar plugin settings and click “Events” box..
It also has a different shortcode

Perfect thanks!