gtk-separators.css

separator, separator:backdrop {
  -gtk-icon-source: none;
  min-width: 1px;
  min-height: 1px;

/* Make window separators transparent this avoids 
   apps displaying separators under toolbar boarders 
   and edges: */

  background-color: transparent;
 }

paned > separator {
  border: none;
  color: transparent;
  min-width: 3px;
  min-height: 1px;
  background-color: transparent; }

paned > separator:backdrop {
  min-width: 3px;
  min-height: 1px;
  background-color: transparent; }
  
paned > separator:selected {
  min-width: 3px;
  min-height: 1px;
  background-color: transparent; }

button separator {
  margin: 1px 1px; }

toolbar separator {
  margin-left: 2px;
  margin-right: 2px;
  border: none;
  box-shadow: 1px 0px @light_shadow;
  background-color: @dark_shadow; }

toolbar separator:backdrop {
  border: none;
  box-shadow: 1px 0px @light_shadow;
  background-color: @dark_shadow; }

menuitem separator, menu separator {
  margin: 2px;
  margin-left: 8px;
  margin-right: 8px;
  border-width: 1px;
  border-style: none;
  box-shadow: 0px 1px @light_shadow;
  background-color: @dark_shadow; }

popover separator {
  margin: 2px;
  box-shadow: 0px 1px @light_shadow;
  background-color: @dark_shadow; }
  
combobox separator {
  background: transparent;
  border: none; }

list separator, list separator:backdrop {
  background: none; }