Also, if by any chance you want to change the buttons size, look for the
.scrollbar section of the same file and and add "-GtkRange-stepper-size:
40;". Or if you want to also change the width of the scroll bar change the
"-GtkRange-slider-width: 20;" value. Mine looks like this:
.scrollbar {
background-image: none;
border-style: solid;
-GtkRange-trough-border: 0;
-GtkScrollbar-has-backward-stepper: true;
-GtkScrollbar-has-forward-stepper: true;
-GtkRange-slider-width: 20;
-GtkRange-stepper-size: 40;
-GtkScrollbar-min-slider-length: 42; /* minimum size for the slider.
sadly can't be in '.slider' where it belongs */
-GtkRange-stepper-spacing: 0;
-GtkRange-trough-under-steppers: 1;
}