Audio pop up notification in XFCE

[matguidi]

Hi, and -- first of all -- congratulations for your great work with this theme.

I use Matcha-sea on Manjaro XFCE, and I have noticed that lately the icon of the audio in the pop up notification (which opens when you raise/lower volume) is (very) light gray, and it can barely be seen. Other icons in pop up notifications (like the brightness one) are OK.

I attach a couple of screenshots.

This is the pop up notification for volume:

This is the pop up notification for brightness:

They should both be like the second one, I think. Thanks in advance!