Can't find style for grouping feature header

Question

I cannot find a way to style the header of the groupping feature. I have tried using the DOM to find a style but no success.

.idOfMyGrid .x-grid-group-row{
}

I want to have two different styles. When the group is closed and when the group is open

Example is here: https://fiddle.sencha.com/#fiddle/2hr. I want to style the header where it says "type".

Answer 1

.x-grid-group-title {
  /* Expanded */
}

.x-grid-group-hd-collapsed .x-grid-group-title {
  /* Collapsed */
}