Gtk3 change progress bar wthin existing theme, Adwaita-dark

Endevouros flavouring Adwaita-dark gtk3 theme and so far I’ve got most of it covered but one progress bar is eluding my manipulations.
When you start gimp for example, the splash image shows with the progress bar at the bottom of it. I’m able to colourize it how I want but not change the height.

Here is part of the section which governs progress bars in Adwaita-dark:

/************ GtkScale * */
progressbar trough, scale fill, scale trough { border: 1px solid #4d29ad; border-radius: 1px; background-color: #282828; }
/* border: 2px solid #1b1b1b; border-radius: 3px; background-color: #282828; 
 * rgba(127, 127, 255 0.7)
xxxx */

progressbar trough:disabled, scale fill:disabled, scale trough:disabled { background-color: #323232; }

progressbar trough:backdrop, scale fill:backdrop, scale trough:backdrop { background-color: #2e2e2e; border-color: #202020; transition: 200ms ease-out; }

progressbar trough:backdrop:disabled, scale fill:backdrop:disabled, scale trough:backdrop:disabled { background-color: #323232; }

row:selected progressbar trough, progressbar row:selected trough, row:selected scale fill, scale row:selected fill, row:selected scale trough, scale row:selected trough { border-color: #030c17; }

.osd progressbar trough, progressbar .osd trough, .osd scale fill, scale .osd fill, .osd scale trough, scale .osd trough { border-color: rgba(0, 0, 0, 0.7); background-color: rgba(0, 0, 0, 0.5); }

.osd progressbar trough:disabled, progressbar .osd trough:disabled, .osd scale fill:disabled, scale .osd fill:disabled, .osd scale trough:disabled, scale .osd trough:disabled { background-color: rgba(58, 58, 57, 0.5); }

progressbar progress, scale highlight { border: 1px; background-color: #7F7FFF; border-radius: 1px; }
/* border: 1px solid #030c17
 * #15539e
 */

I’ve tried adding snippets from:
https://stackoverflow.com/questions/44290651/gtk-progress-bar-height
and a couple of other pages to no avail. Other themes I’ve looked at have different ways of achieving the same goal but it’s beyond me ATM, my 1st foray into gtk theming but I’m quickly getting my head around it.
After my initial edits are done I’ll publish it on pling if I’m allowed of course.
Any gtk wizards out there willing to share some knowledge?