This particular CSS code rotates an SVG upward pointing arrow by 180 degrees only when the header does not possess the .collapsed class:
.IRE-content__header:not(.collapsed) svg {
transform: rotate(180deg);
}
However, an issue arises when the page is initially loaded and none of the headers have the .collapsed class. The rotation effect only takes place after removing the .collapsed class from a header.
This CSS modification is intended for a Bootstrap 4 accordion component.