WordPress: Change Editor Font Size without Plugins

Problem: If you use wordpress and use a high resolution Screen on your Laptop or Workstation the dehault font size is too small.

Solution:

Edit with:

#sudo nano ../wp-includes/js/tinymce/themes/advanced/skins/wp_theme/content.css

change value 13 to 16 or 19 at:
body {
font: 16px/19px Georgia, "Times New Roman", "Bitstream Charter", Times, serif;
margin: 10px;
color: #000;
}