For easy reference here is the CSS snippet mentioned in the video above:

.-logo-bar {width: 45px;height: 45px;}
.-app-title {padding-left: 53px;}

Note that in the "Custom CSS" section of your LearnWorlds site you may find all sorts of ready-made CSS snippets that you can use to customize the look and feel of your LearnWorlds site (e.g. changing the color of your site's navigation panel, hiding whole sections, etc)