diff --git a/templates/official/partial/head.tmpl b/templates/official/partial/head.tmpl
index 82ceb82e..1a7c2342 100644
--- a/templates/official/partial/head.tmpl
+++ b/templates/official/partial/head.tmpl
@@ -19,16 +19,19 @@
   <link rel="SHORTCUT ICON" href="<TMPL_VAR NAME="R_PATH">/static/favicon.ico"/>
 
   <style type="text/css">
+     /* don't display 3rd & 4th column per default */
      td.third_plot_col, td.fourth_plot_col {
         display: none;
      }
 
+     /* show 3rd column when display area width is at least 1900 pixels wide */
      @media (min-width: 1900px) {
         td.third_plot_col {
             display: inline;
         }
      }
 
+     /* show 3rd & 4th column when display area width is at least 2530 pixels wide */
      @media (min-width: 2530px) {
         td.third_plot_col, td.fourth_plot_col {
             display: inline;