Hello @ueffchen ,
sorry for the late reply!
If you still got this problem, you can fix it in multiple ways:
You could change tableWrapper.className = "small mmm-vrr-table"; within MMM-Vrr.js on line 159 into tableWrapper.className = "medium mmm-vrr-table";
Specific font sizes for headeradd another line after MMM-Vrr.css:16 with you desired fontsize e.g: font-size: 50px;
Specific font size within table contentadd this to the MMM-Vrr.css
.mmm-vrr-table tr { font-size: 50px; }