You can add the following CSS declarations to the page MediaWiki:Common.css to gain more space and adjust the alignment when navigation items causes line wraps.
/*Override line height for individual nav items in main navigation*/
#sb-pri .list-group .list-group-item {padding:1px 0}
#sb-pri .list-group .list-group-item > a {line-height:1.4em; margin-bottom: 0.1em;padding: 5px 18px}
#sb-pri-cnt .card-header.menu-title {margin-bottom: 0.8rem;}