.your_target_className {
padding-right:10px;
}

If all you need is that one entry you can put it in your custom.css file located in the css directory of magicmirror like this…

.MMM-Whateveryourmodulenameis .your_target_className {

padding-right:10px;

OR add this to your module:

      getStyles: function() {
       return ["MMM-Whateveryourmodulenameis.css"];
       },

Then create a css file named like the above and enter your info in that…

Like I said if you only need that one entry I’d just shove into my custom.css file…

.your_target_className {
  padding-right:10px;
}

just example.