This makes the element symmetric and reduces the size of the hit target.
With the previous styling, the mid-circle glyph was sometimes offset from the center.
Furthermore, the large font size increased the hit box of the ::after element, eating into the scroll up arrow button's hit target.
It might be a good idea to give the ::after element pointer-events:none so that the scroll up button is clickable in its entirety.
Signed-off-by: Markus Stange <mstange@themasta.com>